Quote:
Originally Posted by NorCalAthlete
An AWD Subaru WRX has a 5.0 second 0-60 right alongside the RWD 435i, but with 32 less hp. So it seems to me that the AWD can help make a car quicker no?
|
I've owned a WRX. The reason these are fast 0-60 is because of the 5K clutch drop phenomena. Rev engine to 5K, drop clutch, go like god kicked the car in the rear due to AWD. Apart from the incredible stress on the clutch, works well enough from a dig. From a roll, not so much. While the latest edition of the WRX is better than the previous versions and engine tunes, these have never been very high HP cars. They are quick at lower speeds due to the above, a little more HP than a base sedan, and short-ratio gearboxes. With a tune, you can improve them quite a bit, but after about 5K they start to run out of torque, even though the RPM will scream up to around 7K (with a tune my rev limit was a little higher than stock). This is due to the size of the turbo. The WRX responds like a turbo car for the most part, with lag and the above effects. Below a certain RPM, it just can't produce the torque to increase RPM (vs. the V8 described below that can cruise all day at 1000rpm AND produce the torque to climb out of it). It can be fun to drive, especially in a "fun at realistic speeds" theme, as in there are cars that will easily pull on it above 80mph, but doing so is going to get highly illegal fast and it doesn't mean much if you live to carve up a mountain road.
BMW's turbo-4 is a little more refined, it's meant to have a very flat torque curve and no significant "lag" where you have to build up to 2800-3000rpm before the turbo really wakes up on the WRX. The twin scroll turbo in the BMW is very close to the exhaust valves and captures a lot of heat and responds quickly, unlike in the subaru. The net effect is a turbo engine that doesn't "feel" like a turbo engine.
Subaru had some very misleading advertisements in recent years, where they said "don't compare our cars HP to other manufacturers, compare the 0-60 times". Subaru had been running pretty low on power compared to other manufacturers (and continues to), but their "edge" was the AWD launch, however punch the throttle in gear and you simply wouldn't go as fast as in other cars. You could however dust the old 230 and 300hp V8 mustangs all day long from a dig, which was fun.
Anything with AWD is usually going to be able to post decent acceleration times, but as the distance gets longer OR the metric is measured from a "roll" in gear, the performance gets worse comparatively.
On the other hand, my Camaro SS could stick sub 5s 0-60 because it had large wide tires and torque for days, the trick is not spinning the tires, but that just means that it wants to go, regardless of what gear you are in.
I don't think you'll find the X-drive 435/440 to be "faster", only that it will do the 0-60 launch faster and possibly be faster in the 0-30mph range, this is where AWD has an advantage and won't spin the wheels nearly as easily as RWD, but a RWD with decent width and rubber will put it's power down just fine at most speeds, unless the car is speced with tires too skinny or too hard. Keep in mind, my 0-30 thing is only "at the limit", your maximum acceleration, which you probably won't be doing from every stop...
There are some cars that have so much HP that it's pretty easy to spin the wheels in many gears besides 1st without electronic aids. These will accelerate faster at times or in certain situations when they are AWD, but the BMW isn't one of these, not to the extent where it's sending 500hp to the rear wheels or anything...
I didn't buy the 428xi to be the "driver's car", I bought it because I live in Alaska and needed the AWD capability for hills and iced (not snow, but glare-ice) roads. It handles ok and when pushed with the DHP, it's decent, but it's not a performance car as far as the handling goes. Get a boxer, BR-Z or something like that if you want to get back to handling. BMW handicaps the Xdrive by making the ride height higher and not offering sport suspension.