Originally Posted by Should be Working
Haven't been on the forum for a while, so apologies if you have seen this before. read an interesting article in Autocar the other week about actual power available at the wheels against quoted power. Audi RS4 seems to be the main culprit losing a massive 68 bhp (16.5%) throught the 4 wheel drive transmission. The BMW M5 loses only 7% as it is 2 wheel drive. Should make for an interesting comparison if the E92 M3 has similar losses to the M5.
M3 - 385 bhp at the wheels
RS4 - 345 bhp at the wheels
Sounds like it could be an ass kicking for the RS4 to me (unless it's wet!!)
There are a number of threads on here about WHP vs CHP. A few important notes. You CANNOT attribute differences SOLELY to drive train loss. This is evident from the fact that some cars are gaining HP at the wheels relative to their crank HP specification.
The other factor (which certain parties here in the past have failed to take into account) is that some cars power/torque numbers underrated (this is done for a variety of reasons).
It is also important to consider that there are variations from car to car even for a specific model. This means that they could have had a ringer for an M5 and a dog for an RS4, increasing the gap. Of course they could have had a ringer RS4 and a dog for an M5. It's just important to note that it's NOT a sampling. 10 M5s and 10 RS4s from a variety of production dates would be a more telling story.