Originally Posted by mixja
The problem with the above comparison is that although it takes into account the gearing of the car in terms of torque to the wheels, it doesn't take into account the effect of the gearing in terms of vehicle speed.
Because the 335 has a taller ratio in 1st gear, it travels further in a single engine revolution - the best way to take this into account is to plot vehicle speed (rather than engine RPM) vs torque to the wheels - this gives a more accurate picture of what will actually happen in terms of the relative acceleration of the two vehicles.
In effect, the taller gearing will stretch the torque curve of the 335 to roughly the same width of the M3 curve, when you apply vehicle speed on the X axis rather than engine speed...
Here's rear wheel torque vs. speed if that's what you are looking for. Obviously, rear wheel torque depends on gear so I show that as well. Again, the engine can't stay in the same gear over the entire speed range so I just select the gear with the most rear wheel torque and show the rear wheel torque for that gear. The spreadsheet doesn't use engine speeds above redline. This spreadsheet takes into account gearing (transmission and diff) and stock wheel size.
It does seem that both a stock MT 335 and MT M3 have near the same optimal shift point.