Quote:
Originally Posted by walile
But the rear wheels can lose traction first under power. Don't forget that. Imagine if a driver is driving a powerful RWD car in low traction conditions. Say he wanna pass the car in front of him and decided to steer and apply full throttle. Idiot move but hey people do that.
With no TC/ESP, he can oversteer and spin. With TC/ESP, hopefully the system will intervene and cut power before he kills himself. Note that ESP is a passive system and slows you down.
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While I certainly won't disagree that AWD can appropriate less torque to the rear wheels, the culprit in this scenario is providing too much input. Whether this is steering or throttle, the driver is the one inducing the loss of control. The affect of AWD, especially a reactive system like xdrive, will be pretty marginal compared to the timescales ESP is able to actuate at. Even a torque sensing AWD system like quattro will likely do little to mitigate hydroplaning.
An interesting exercise in understanding the understeer/oversteer dependency on throttle input involves driving in a very tight circle at high speed. You can actually change the radius of your circle by applying throttle more/less. This works regardless of drivetrain.
Quote:
Originally Posted by walile
With a good AWD system, some power is shifted to the front to prevent the rear wheel from losing traction. Again, AWD actively provides more traction. Definitely provides more performance headroom.
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Yes, I definitely agree with this. But one must also understand there is a difference between (a) "predicatable" scenario where torque appropriation needs to shift - such as launching the car from a stop, or WOT when cornering; (b) unpredictable scenario such as ice on front tires, which requires either sensors to detect it or torque sensing in the differential (torsen for ex).
Quote:
Originally Posted by walile
I don't remember torque vectoring being mentioned anywhere in the brochure. There is a eLSD function that simulate the function of a LSD, but that's no torque vectoring.
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I'll look for it and post the link...