Originally Posted by southlight
Assuming that both cars had the stated engine power the conclusion is that the M3 has much less drivetrain loss than the RS4.
The M3 brings 45hp more power to the wheels (both have the same stated engine power, 414hp) and even the same amount of torque to the wheels (RS4 is stated with 317 lb/ft, M3 with 295 lb/ft).
Anyway the drivetrain loss of the M3 is higher than the M5's and 335's, which means either that M3's drivetrain is less efficient or that M5 and 335i are underrated (which is more likely).
Best regards, south
Why do you suppose peak power on the M3 was measured at 7,808 rpm vs. 8,300 as spec'd?