[Jumbosock]

I've owned both E46M3 and Z4M. There is a distinct difference in sport mode between the two cars (unless a service update has changed things since 2011).

One of the main differences is when you have the accelerator pressed while hitting the sport mode. In the E46M3 if you are at anything less than full throttle you will instantly feel the sudden change of sensitivity in the pedal. It is a very obvious change. In the Z4M you will feel no change in this same scenario. In the Z4M the system waits until you release the pedal before applying the new pedal sensitivity. I think it does this to avoid a rough transition. That's the main difference. Once the sport mode settings are applied, the difference in pedal sensitivity is very obvious.

When I first got my Z4M, after owning an E46M3, I thought the sport mode was broken until I realized I had to release the pedal before the sport mode initiated.