I know how to use it, but I don't know exactly what it does. Increase RPMs? Ummm...???

 

On the 325i I got as a loaner, the Sport mode plays on how the transmission behaves...

It will stay in lower gears longer, and will go the the redline if I drive it a bit "sporty". It will also downshift if the RPM goes below 2-2500rpm.

It makes a good difference on the way the car drives and a lot more fun to drive.

 

I don't know about the automatic downshift part (I haven't noticed that; but it may also be a result of how I drive the car), but SD on the MCSa raises the upshift point about 500 rpm. Also, SD uses only 5 forward gears. That is a little counter-intuitive, but it definitely only uses 5 forward gears. And, gas consumption is about 2 mpg less.

 

In the little info I could find w/Google... ...I read in a review that it does use only 5 gears. I guess that's basically narrowing the gear ratio to crank up the RPMs/torque. ???

 

Well, I doubt that MINI/BMW used way to bump up the RPMs. The transmission upshift point is controlled by the DME. In the MCSa, there are two (actually three) modes for the auto transmission (D with one set of shift logic, SD with another set of shift logic, and M with a further set (not letting you shift into a gear that puts the engine into over-rev or under-rev) of shift logic). The reason I mentioned the counter-intuitiveness of 5 vs. 6 forward gears in SD is that with SD being the performance mode of the transmission, you would think that you would get all 6 forward gears at higher shift points. But instead, you only get what seems to be gears 1-5 with higher shift points. For comparison, the M3 SMG option in its most economical mode (D1) starts out in 2nd gear....