dimanche 17 novembre 2019

2004 Audi TT 3.2 Quattro DSG Track Review



Before getting into this, I have to confess something... I had never driven an Audi TT before. Not until this one, anyway. But that hasn't stopped me from forming an opinion about it from the comforts of my own couch while reading and watching reviews online. After all, if you've never done that, do you even know what the point of the internet is? Now, we all interpret reviews differently. Call it confirmation bias if you will, but if you like a car, you'll read a review and look at the positives as what makes the car great and the negatives are but a few quibbles you have to live with. If you don't like a car, the positives are a few things the manufacturer got right while screwing up everything else. It's a bit harsh to put the TT in the latter category, but that's where it ended up for me...

I never took the TT seriously. The problem with the TT for me isn't that it's a Golf underneath, per se. There is nothing wrong with a performance car sharing a chassis and a drivetrain with a humble nameplate (as long as you don't call it a "sports car"). That's specially true when the humble nameplate is built on very good bones. There isn't a hot hatch out there isn't built on a humble nameplate. The problem in this case is the (hot) hatchback itself; the Golf.


What's so special?

The base TT was FWD and had a 1.8 litre turbocharged 4 cylinder, just like a GTI. It was tuned to make more in the TT with about 180 hp but that was nothing to write home about. You could get it with more power and the same engine in a higher state of tune, more boost, and a bigger turbo making 222 hp, but that sounds more like an aftermarket tuner fiddling with the car, rather than something special. A few years after it was released, you could get it with VW's 3.2 litre VR6 engine, but they went and dropped that in the R32 as well. Quattro? It isn't a real Quattro, it's the same type of Haldex system VW used in 4motion and R32 models. The question is this: why get it over a Golf? It's just a Golf in a fat suite (or, a skinny suite, rather... and a fraction of the utility). But I was wrong.

I remember an episode of Top Gear UK quite a while back where they reviewed the Aston Martin Vanquish and they kept saying that they couldn't justify it over the DB9. The two Astons were as close as makes no difference in terms of size, looks, engine, power, speed, etc. yet the Vanquish was a lot more money. But at the end, Jeremy figured it out. He said the Vanquish is a DB9 "where every little thing is made a little bit better." THAT is exactly what the TT is to the Golf.


The TT is a little stiffer. It handles a little better. It's much lower to the ground with a lower centre of gravity. It has a wider track and a narrower wheelbase. Wider wheels and tires, bigger brakes, more power, when properly spec'ed. And of course, it looks nothing like a Golf inside and out and it feels smaller thanks to the cabin and dimensions. Combine all of that together and you have something that feels completely different.


The Handling

This TT isn't stock (unfortunate for the objectiveness of this review, I'll admit). It has a set of ST coilovers. I'm not familiar with ST to be honest, so I don't know if they're high end units aimed at track use or not. Their price suggests they're middle of the road, but there are no complaints from me. The car was flatter than the Bonneville Salts. Body roll is a distant, faint reminder that the car does have a suspension. But it isn't just a rock stiff setup. Small undulations are entirely shrugged off. I couldn't do the ultimate test of a suspension - riding the rumble strips in the apex - because it wasn't my car, but nothing upset the chassis. 

There are a few bumps on our track that seem to have been strategically placed to mess with you. One is just past cresting a little hill (Turn 5). The car is a unloaded at that point, it's just after the apex of the turn so the car isn't straight, and it leads to our "back straight" (it's not entirely straight) so you need to get back on power ASAP. Any speed you lose here amounts to a big time loss by the end of the "straight". Add in a few bumps, and you are really testing a car's suspension tune. This TT didn't like it (at first)...



I didn't know if it was the springs or the dampers, but I figured going softer would help the car. The car is also very low so I thought it might have been bottoming out in the back (owner checked this later and confirmed it was bottoming out, more on that in a bit). There's just so little suspension movement. But even with that in mind, it never once threatened to bite. If you trust the car and point it in the right direction, it will take the bumps and carry on. 

And it gets even better. Since the coilovers are height adjustable, the owner raised ride height in the back to see if that helped in case it was bottoming out and that was a huge help. You can attack any turn flat out now with no hesitation. And the slight increase in ride height in the back must have shifted a little weight over the front axle because it feels a little more eager to turn. The extra ride height and suspension travel meant the car just shrugs off every bump and dip, despite the stiffness. Combine that with the improved front end grip, and the results are incredible. It's still easy to find understeer at the limit, just come in too hot and the front end will run wide. But it doesn't plow straight and it's very well behaved on power in corner exit. The upside to the stability is that you feel like you can throw it into a corner and it'll never go wrong. 


This is all made even better by the steering. Feedback is great compared to the majority of modern cars I've driven on track. The brakes (all stock except for pads and SS lines) have great feel, great bite, and fade resistance. The wider track and shorter wheelbase - two of the advantages of the TT suite over the Golf body - make it feel more nimble, agile, and eager to change direction. All of that, combined with sitting lower in the chassis make you feel that much closer to the action (contact patches) so you can feel a lot of what's going on at the tires.

The Drivetrain

The 3.2 litre V6 (VR6) engine is such a joy. It has good power everywhere, revs freely, and makes a great noise. Like the suspension, the engine wasn't stock either. It has full exhaust and cams. It sounds great, easily one of the best sounding V6's out there. I always thought to myself that if I were to get a TT, I'd want the 4 cyl turbo because of potential to make more power and tuneability but no, give me this over the turbo any day. Power is immediate and so easy to modulate, the noise is miles better, and being naturally aspirated means no turbos, intercoolers, and additional heat and plumbing to worry about. 



I probably would've liked to drive this car with a manual, but it's hard to complain. The transmission shifts quickly and holds gears to redline. It doesn't feel like it's holding the car back in any way. Want this car with a manual? I would too. If you want it with a DSG, though, I wouldn't blame you. 


Lap Times

This is an area where - unlike the driving, which pleasantly surprised me - I was disappointed. Given the modifications and the grip, I was expecting more. I did one 1:27.2 lap followed by two 1:26.9 laps. That's the best I could manage. In addition to the power and suspension mods, the car is on Nankang NS-2R tires. Grip felt good, really good. I could carry good speed into the corners. The balance, as mentioned, was great. I think the biggest problem is the power. The car couldn't crack 95 mph on the back straight and barely cracked 80 mph on the front straight. Between the corners, I had no problem keeping up with another Boss 302 on track in the turns, but it was seriously down on power otherwise.



It's worth noting that I've driven this car 3 times so far. Twice was in 80+ deg F (28+ deg C) weather - including this test - and once was in 60+ deg F (15 deg C) weather, according to dash readouts. The difference in power as measured by my butt dyno is massive. I was very underwhelmed by the engine the first time and told this to the owner. But in cooler weather, it was a different animal. The owner agrees.

The engine feels alive in cool temperatures and eager, seemingly always tugging at the leash. In hotter weather, it feels very subdued. I imagine the engine tune might be conservative given that it's a track tune. Heat alone kills power due to a less dense air charge. Combine that with (potentially) a conservative tune that aggressively pulls timing to protect the engine, and you probably have a significant power difference in heat. I figure this car can do a low 1:22-1:24 time with better conditions. Hope I can find out at some point.


The Verdict

Although it's still FWD-based with a Haldex AWD and a relatively heavy V6 up front, it's very far from the terrible understeer that such a setup might conjure. Turn in is great and there's good front end grip. A bit of trail braking rotates the car very nicely once you start carrying more speed, yet it'll never bit. And corners that don't need braking just need you to back off the throttle just a little on turn in and the nose tucks in beautifully. I'd want a bit more mechanical grip up front. The tires are staggered 225/255 front/rear. A couple of times running hot into T1, the car ran quite wide. I don't think I'd change the suspension balance of the car, just a bit more tire up front should do the trick.



The forgiving and communicative chassis combined with AWD system makes it very (very) easy to drive fast. The car doesn't have an active suspension to help cover up your mistakes. There are no active diffs and million mode traction control systems. It's just a forgiving chassis and a boat load of traction. The owner even turned off stability control for my most recent drive to avoid having power cut out to get a lap time. But there was still no shenanigans. There are few cars other than my own that I feel comfortable pushing this close to the limit on track without the assists. This is certainly one of them.

I'll be the first to stand in line demanding the return of manual, RWD cars if (when?) they're all dead. For competitive rats like myself, it's far more satisfying and engaging to play with a well balanced RWD car. But after a day of pushing my much more raw and demanding Boss 302 at the Time Attack, there's genuine appreciation for driving this TT. It's speed without much drama, and not the sort of easy speed you get these days with modern cars that do a lot of work for you. No, you still have to drive the car properly. Short of the AWD system shifting power to the back when the fronts call for help, this is very much an analog car and you have to know what you're doing to drive it quickly. But when you do, it'll reward you with great feedback, effortless speed, and one of the best V6 soundtracks out there.


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lundi 4 novembre 2019

Why Sim Racing?



Sim racing is a fantastic way to improve high performance driving skills. There are many obvious benefits to sim racing, but the two primary ones are safety and cost. Safety is obvious, as there is no risk of physical crash or injury in sim racing. Cost is also obvious, since it is far less expensive to have a home sim racing setup than it is to buy, maintain, and run a race car.


Can Sim Racing Help in Real Life?

Absolutely. Nissan and Sony ran a driver training program called Nissan GT Academy which ran for six seasons and helped develop and train successful Sim Racing competitors into real world race car drivers and establish experience gained through sim racing as valuable training time for actual racing in the real world. The program had more than 5 million participants (Wiki). Earlier this year (January, 2019), Enzo Bonito – an eSports sim racing competitor – competed against Lucas Di Grassi – a professional Formula E Champion – and beat him at the Race of Champions weekend in Mexico. It is no longer possible to dispute that the skills gained in sim racing can transfer to the real world.

Professional racing drivers now use racing simulators to practice before races (and have for a while). As sim racing software and even realistic video games such as Forza and GT get more sophisticated and capable, the benefits of sim racing can translate to the real world. The physics of weight transfer, managing grip, overall grip limits, spring rates, damping rates, alignment, etc. are all simulated in good racing simulators. How does something with a lot of weight over the front axle like a FWD compare with something like a 911 with the opposite weight bias? Or a front engine RWD car? Or a mid-engine car? Developing a better appreciation for the physics of high performance driving is a huge benefit to racing.


Another very important benefit is developing muscle memory. Particularly, how quickly you can adjust your steering to correct oversteer, or how smoothly you module throttle and brakes. With high quality controllers that simulate feedback and forces, it is possible to work on all those skills. You can even work on heel and toe downshifting or left foot braking. Not mention, developing and learning race craft; the art of wheel to wheel racing. All of that is also possible to practice in a very wide variety of cars, most of which would not be accessible to the average driver. Those skills and others can be developed and honed in sim racing and will be a huge benefit when you step into a real car.

Finally - and perhaps controversially - it can help you get somewhat familiar with a track. This one can backfire badly, because some people can show up to their first HPDE thinking that they don't need help if they are good sim racers and happen to have a lot of experience at the particular track they're learning on. That's absolutely the wrong attitude to bring to the track. But if you don't approach it that way and just use it as a tool to gain some familiarity with the track, it can be very useful.


Can Sim racing teach me everything?

This is a well debated topic when it comes to sim racing. In my opinion, sim racing can't teach you to manage a healthy respect (and to an extent, fear) of a crash. While you can feel a lot of pressure to avoid crashing for ratings and final race standings, fear of damage, injury, or worse is never a factor. The risk of crashing on a track is real, though, and managing track safety is paramount whenever you're out on track, be it competing or lapping. And that's not the only thing.

For the vast majority of people buying sim racing equipment with no motion simulation, sim racing can't teach you to pick up on the car's reaction to all your inputs, what g-forces actually feel like, what the car is trying to tell you, what the tires are communicating, etc.. You can't develop any physical sensation of speed. You also can't learn to pick up on noises and warning signs that something is about to go wrong so you can go to the pits and check it out.

If you plan to never leave the virtual world, then you don't have to worry about those factors. But if you hope to one day step into a real car (or if you already drive competitively), it's important to appreciate the limits of sim racing when you make the transition. This will also help better recognize the benefits and strengths of sim racing. Not to mention, enjoy how much fun it is! (especially if you live somewhere where track closes in the winter due to weather...).


Great! How do I start?

The best place to start is with a good sim racing cockpit. As with real racing, you need to be comfortable to go fast. Good ergonomics go a long way in making you more comfortable to push and improve consistency, a true mark of a good driver. That's why you need to pay attention to picking a good cockpit. But good ergonomics alone aren't enough. You also need good high quality controllers that can simulate the feel of driving a real car and, ideally, a sim racing motion simulator.

There are lots out there and I've found that it's very common to wonder what to pick in the endless options of controllers and cockpits. That's why I've spent a lot of time researching sim racing equipment options and picked those that best combine immersion, quality, and value. You can conveniently shop for everything we carry at Pit Lane Sim Racing with free shipping all across Canada (if you're shopping from the US, bear with us and we'll do our best to have that sorted out soon!).


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mardi 29 octobre 2019

Cadillac ATS-V Track and Road Review Video


Does the Cadillac ATS V live up to its mission of challenging the BMW M3? There is no better way to find out than a couple of days at the track and a nice back road drive. Stay tuned for a review article soon and if you like the video, make sure to subscribe for more upcoming videos! (with a new mic and better audio next time...)


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vendredi 11 octobre 2019

2020 Mid Engine Corvette C8.R Race Car And Engine Specs Revealed


It's finally time to welcome the brand new 2020 mid-engine Corvette C8.R race car. I'd say this is the most hotly anticipated race car to debut since the current Ford GT, but Ford surprised the world with the GT so there wasn't a whole lot of anticipation. This may be the most hotly anticipated new race car ever in quite a while, much like its street going mid-engine sister.

It's the first clean sheet design in about 20 years, Chevy says, since the 1999 C5.R and will race for the first time ever at the 2020 Rolex 24 Hours of Daytona. Chevy says there is a deeper connection and technology transfer between the C8.R racing version and the road-going C8, and the highest percentage of shared parts of any Corvette generation before.


In fact, the C8.R utilizes the production chassis built right alongside the other chassis meant for street duty in the Bowling Green Assembly plant that builds the street version. As expected, there are some modifications to meet race requirements, likely including at least additional welding or adhesives. The new chassis is stiffer and lighter than the C7.R, as expected. And, of course, the engine is also like nothing else seen in a Corvette race car, or road going Corvette for that matter.

It's a 5.5 litre naturally aspirated V8 just like the outgoing one, but that's where the similarities end.




Chevrolet teased the engine exhaust note last week at the Kennedy Space Centre reveal and it sounds like no other Corvette before. I told a friend of mine: "It sounds like an older uncorked Ferrari! Flat plane and no turbos." And sure enough, it will be a naturally aspirated flat plane crank engine complete with dual overhead cams and direct injection. Chevy hasn't revealed much else about the engine, only that it will make about 500 hp and 480 lb-ft of torque. Chevy made sure to point out that this engine isn't (closely) related to the twin-turbo 4.2 litre Cadillac version. 

What's even more exciting is the all but guaranteed expectation that a variant of this engine will find its way in a street-going version of the C8 Corvette. Due to FIA LM GTE rules, the engine "must be derived from a series production engine produced at more than 300 units and fitted to a series vehicle from the same manufacturer." According to Road & Track, a Chevy representative confirmed that it is a "future production-based engine." Are you feeling giddy yet?


If you aren't a Corvette fan, this all sounds like PR and marketing mumbo jumbo. A late showing to the (mid-engine) party after Ford brought back the GT and even Porsche going mid-engine with the 911 RSR. But if you are a Corvette fan (or a fan of affordable sports cars offering incredible performance), this is all very exciting. If that's not enough, watch this little promo video Chevy put together. It may make the hair on the back of your neck stand.


If you can't wait to see it run, Chevy will be taking the new car for a parade lap at Road Atlanta this weekend for Petit Le Mans. Until then, see you at Daytona! Oh, and don't worry. Jake is still alive and well!



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samedi 28 septembre 2019

GTR vs Evo X vs STI: which has the best AWD system?


A few weeks ago, I made a post explaining mainstream AWD system types and how they compare, pros and cons, etc. including some simple diagrams to show where the power goes and how much. As promised, this post will focus on specific cars and what AWD systems they use, especially ones that that have more or less been defined by their AWD systems, and the best place to start may be with a bombshell; the Nissan GT-R.


Nissan GT-R (R35)

The GT-R has built a reputation around having monster traction and very approachable performance, thanks to its AWD system - Advanced Total Traction Engineering System for All-Terrain (ATTESA) - and what it can do for you. But the GT-R doesn't actually use the most mechanically sophisticated type of AWD systems discussed in the previous article, namely a "true" AWD with a centre differential. Instead, it uses a clutch pack to transfer power.

RWD-based clutch-type AWD schematic - Rams Eye The Track Guy ©

The R32, R33, and R34 Skyline GT-R's used a system that looked basically identical to the traditional RWD-based clutch type AWD system digram. This is the same type of AWD architecture you'll see in BMW X-drives, Cadillac RWD-based AWD cars like the ATS and the CTS, etc. Front engine > transmission > transfer case > power split, with a clutch pack in or at the transfer case controlling how much power you send to the front axle. The R35 GT-R is hugely similar to those older Godzilla's, with the main exception being a rear transaxle instead of a front transmission.

Instead of the transmission being bolted directly to the engine, there is a rear transaxle (transmission/differential as a single package) located at the back for better weight distribution. Power goes from the engine to the transaxle using a torque tube and then you have a drive shaft/prop shaft running back again to the front axle from the rear transaxle to send power up front. Like the earlier GTR's, a clutch pack varies lock to control how much power to send up front. 0% lock sends no power to the front, all power going to the back. 100% lock splits power evenly (50:50) between front and rear, with infinitely variable adjustment in between.

RWD-based clutch-type AWD schematic with rear transaxle - Rams Eye The Track Guy ©

So what makes the GT-R special and why not use a centre differential? Well, a clutch-type AWD system is actually very capable as mentioned in the previous post. It is very flexible because it can control exactly how much power to send to the secondary axle simply by varying clutch engagement. A "true" AWD system with a differential has a fixed torque split which, while can be biased to the rear axle for better handling, is still fixed. It can never act like a RWD car if you don't need the extra traction in the front. It's always splitting power between the front and the rear axles. The only time it modulates power split is if one axle (i.e. one or both wheel/tires on one axle) starts to spin AND you have a limited slip mechanism to send power to the axle with more traction.

What does this mean on track? It means that the GTR sends almost all of its power to the back and only sends power to the front as needed to utilize available traction. When it does, it only sends as much power to the front as needed to avoid overpowering the rears, no more. The exact same reason why those "part time" AWD systems got a bad reputation in FWD-based cars (i.e. always driving the fronts until fronts lose slip) is the same reason they are great for RWD-based vehicles; they're mostly RWD vehicles except when you need more traction. The downside to those systems is two things:

1. Unlike a true AWD system that always splits power, this system has to "act" (or react) to transfer power, meaning there is a time delay between the computer deciding it needs power up front and actually sending power up front.
2. It can overheat due to the constant slip of clutches in the clutch pack unless they are fully locked, which is rare.

R35 Nissan GTR at Atlantic Motorsport Park - Graham MacNeil ©

The GTR gets around both of those issues by using a high capacity, high pressure, fast acting hydraulic system that activates and modulates the clutches much faster than a traditional clutch-based AWD system like you'd find in a BMW or a Cadillac (or FWD-based AWD system like Haldex). As mentioned in the previous post, if the system is sized properly to handle the heat, it can be very powerful.

What makes the GT-R system even more powerful is that it uses an active rear differential that can vary lock, much like the electronic limited slip differentials described in my earlier post Limited Slip Differential Types Compared. Short of a torque vectoring differential, this is the most capable limited slip differential you can get. It's the same type Chevy uses on Camaro SS 1LE and ZL1's and Corvette Z cars, the same one used in BMW M cars, and the same one Porsche uses in the 911 GT3 RS and GT2 RS. All of those cars are RWD and they make such great use of available traction at the rear axle alone using just an electronic limited slip diff that they can beat just about anything on track. Imagine what you can do with the same type of system, coupled with the ability to send power up front as needed when you do exceed the rear end grip.

R35 Nissan GTR at Atlantic Motorsport Park - Kevin Doubleday ©

In short, the GTR maximizes use of every ounce of available traction at the back. When you do exceed the available grip in the back, the fast acting clutch pack carefully (but quickly) modulates power to the front axle as needed to avoid the rear axle losing traction. This means you avoid using the front axle as much as possible to leave it for steering and braking duties like a RWD car AND you maximize use of available traction at all four contact patches whenever you need. In other words, it's called Godzilla for a reason.


Mitsubishi Evolution (Evo) X

Unlike the GTR, the Evo X and previous Evo's use a "true" AWD system. Born and bread in the world of rallying, the Evo needs a more robust and consistent system. Rallying is like offroading for speed freaks. As mentioned in the previous AWD post, most hardcore offroaders like traditional 4x4 systems because they are dependable and consistent. You put the car in 4x4 (or 4 high/4HI) and power is always split. No computer guessing or variable power distribution. Using a centre differential instead of a clutch pack means consistent and fixed power split front to rear.

Mitsubishi Evo X AWD Schematic - Rams Eye The Track Guy ©

With that said, as mentioned in why open differentials don't work on track, an open differential alone can only send as much power as the low traction side can handle. On an axle, that means the wheel/tire with the least traction dictates how much power the other wheel gets gets. In an AWD system centre differential, that means the low traction axle determines how much the other axle gets. To avoid this problem, the Evo X uses an electronic limited slip centre differential that can variably lock the front and rear axles together to limit slip at either axle as needed. Earlier Evo's were mechanical but the late model Evo's use an electronic limited slip differential, using an electronically controlled clutch pack to lock the two axles together if one axle starts to spin.

The schematic is not an exact representation of the physical arrangement of components inside the Evo's transaxle because that makes it more difficult to illustrate the flow of power. Red is the centre diff housing and it gets engine power. It splits power between front (grey) and rear (black) axles. An electronic multi-plate clutch pack (green) can variably lock front and rear axles if either starts to spin. In essence, the Evo takes the rear differential type of the GT-R and puts it in the middle. What that does is distribute power between the front and rear axles as consistently and effectively as possible.

Mitsubishi Evo X at Atlantic Motorsport Park - Kevin Doubleday ©

After that, the Evo uses a gear-type mechanical (like Torsen and Quaife) front limited slip differential to maximize available traction up front. In the back, it uses a true torque vectoring differential to control how much power to send to either side. That allows maximizing use of available traction at the back like the GTR, but goes one step beyond that by inducing steering moment/yaw at the back if wanted by sending torque to the outside wheel.

What does this mean on track? It means that whenever you put your foot down, the Evo X is always splitting power between the front and the rear axles and does its best to maximize use of traction at every contact patch. It uses limited slip diffs front and back (torque vectoring in the back). With a transverse engine layout ahead of the front axle and a front transaxle, the Evo X has a balance that approaches a FWD car instead of a RWD car like the GTR, with most of the powertrain and transmission weight ahead of the axle and a roll centre ahead of the driver. The Evo takes advantage of that by allowing weight transfer to the front to maximize front grip but, at the same time, has all the tools in place to send power away to the rear axle. as needed to avoid overpowering the fronts.


Subaru WRX STI

The STI is designed with a very similar mentality to the Evo X. The main difference is that it has a longitudinal flat-four boxer engine as typical for Subaru and a longitudinal transmission like a RWD car. Like the Evo, however, the STI uses a centre differential to consistently split power between the front and the rear axles. Up to 2017, the STI used a mechanical centre differential - a Torsen, like an Audi Quattro system - plus an electronic clutch pack just like the Evo to provide additional lock as needed, up to 100% locking if need be (a Torsen cannot provide 100% lock). As of 2018 and beyond, the STI makes do with only an electronically controlled limited slip differential.

WRX STI AWD schematic - Rams Eye The Track Guy ©

Up front, the STI is once again similar to the Evo and uses a gear type Torsen limited slip differential in the front. In the back, however, the STI uses another Torsen limited slip differential instead of an electronic differential. It then supplements all the differentials using variable brake lock to slow down individual excessive wheel spinning. You can read more about using the brakes to limit slip in the earlier post Limited Slip Differential Types Compared. It's the same technology used in a very wide array of specially marketed cars from off roaders (Jeeps) to hot hatches (Focus ST, GTI without performance pack or PP) to even supercars (McLaren).

What does it mean on track? Like the Evo and unlike the GTR, the STI is always splitting power between the front and rear axles. In power distribution, however, it is stuck somewhere between the two. The STI has a front to  rear power split of 41% to 59% (absent lock up from the centre clutch pack).

4th gen WRX STI at Atlantic Motorsport Park - Kevin Doubleday ©

Driving it, it does not seem to be designed to allow weight transfer to the front for added grip and agility, not as much as the Evo anyway. You can read more about how the two compare in my Focus RS vs STI vs Evo X comparison. Long story short, the lack of a torque vectoring rear differential and the handling balance (i.e. further from neutral) indicates how the STI was balanced, which is not to encourage rotation, but simply to promote stability. The rear power bias lets it take better advantage of stability (i.e. more grip at the rear axle) but never at the expense of traction. If you want to slide or rotate the STI, you have to grab it by the scruff of the neck, chuck it into a corner, and give it a boot full of power.

Which one is best?

The burning question is which one is the best AWD system. You can't know for sure what the designers of each system were thinking, but you can kind of guess based on background and application. Nissan comes from a background of sports cars and road racing. It is thinking in terms of a sports car - front engine, RWD. Its solution to increased traction is obvious. Build a RWD-ish sports car with best type of limited slip differential (short of torque vectoring) to maximize use of available traction at the rear axle, then add an electronically controlled clutch pack to send power to the front as needed to improve traction.

R32 Nissan Skyline GTR AWD at Atlantic Motorsport Park - Kevin Doubleday ©

On the other hand, the Evo and the STI come from a background of rallying where speeds are high on low traction/low grip surfaces and you always need to be splitting power. Their AWD systems reflect that. If you're always splitting power, the best system is a true AWD with a centre differential. Then they employ limited slip mechanisms/technologies at the front, centre, and rear differentials so that power can be distributed side to side and front to back to make best use of every little bit of traction you can find. But I wouldn't be surprised if the STI (and the Evo if Mitsubishi ever brings it back) does away with their centre diffs in favour of electronic clutch packs as controls and heat handling capacity of those systems get better.

All three cars - if stock/factory - will understeer at the limit. But they behave differently up to that point. The GTR feels like a very safe and approachable RWD car with mountains of traction. A RWD car that never wants to bite. It understeers the most at the limit, but it gives you the most flexibility in using power to rotate the car with the most rear bias. The Evo X feels like a playful hot hatch that never runs of front end grip and claws its way around a corner like a far lighter and more nimble performance car. The STI is somewhere in between. It doesn't feel as tossable and playful as the Evo, feeling more like a RWD car. The upside of that is that you can kick the back end out if you have power biased to the rear using the C.Diff controller.

4th gen WRX STI at Atlantic Motorsport Park - Kevin Doubleday ©

On the road in poor driving conditions (ice/snow), the GTR system is, theoretically, the least capable. It has no limited slip mechanisms up front and sends most of the power to the back until there is slip. While it is a very fast acting AWD system, I can't be convinced that it is as good as consistent power split. The Evo and the STI are better, in my opinion. This is not surprising since the Evo and the STI came from driving (very fast) in "poor" driving conditions. They both are always splitting power. The Evo system is more agile but the STI system feels more secure and is the one I'd prefer driving in Canada winters, but I'd rather drive the Evo on track.

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