Originally Posted by footie
I have no way of proving this but I reckon BMW have chosen to use high revving N/A engines of modest capacity to insure that the torque levels are only produced to the upper levels of the rev range. This means that gearbox, driveshaft, diff, etc., can be made as light as possible in comparison to the likes of the C63.
I guarantee that if the engine/drivetrain complete for both the M3 and the C63 were laid out in front of us and weighed, we would find that the M3 (even an M-DCT equipped one) would be much lighter. It's one of the reason for their remarkable low draintrain lose...
M marketeers here in the states make this point in articles and in person. It certainly makes sense up to a point - but only up to a point.
Let me contrast the BMW with the latest ZR1 Vette to show how limited the point can be.
At the transmission output in first gear, the 604 pound foot Vette is twisting the drive shaft to the tune of 1383 pound feet, which is of course a considerable amount. By contrast, the paltry 295 foot pound M3 is making 1197 foot pounds at that point - or nearly 87% of the Vette's number.
At the rear half shafts, it's even closer, with the M3 at 4611 foot pounds, and the Vette at 4730. Hell, you could probably use the same half shafts with half a heat treat difference.
One would need to do a direct car to car comparison between the M3 and each of its competitors to see how much of a difference M philosophy might actually make. Still good, mind you, but not necessarily huge.