Cartmanizm

Hey guys,

Trying to work out a the quickest way to launch off from a set of lights. I believe in D/S mode (auto) by itself isn't the best since it starts on second gear I believe? So the best way would be to throw it in semi-auto mode in first gear, turn off DSC, and press down on the brakes and slightly give it a bit of rev. Now 2 questions I've got:

1. I know that simultaneously holding down the brakes and applying a bit of throttle isn't great for the car, but how bad is it? Apart from extra wear and tear to the brake pads, is there any other negatives?
2. Now I've noticed that when in semi auto D/S mode, the gears actually automatically shift at redline, is this the most optimized shift points when launching off at the lights? Is this bad for the car?

I've got a 07 530i LCI btw.

Thanks!

jaycal3

I always thought "D/S" started in first, and "D" starts in 2nd... The shifts in D/S mode are supposed to be at the optimal times...

PaoChe

Well redlining your engine is never good for it. So is it bad? Yes, if you do it all the time.

D/S and the manual/auto shifting are essentially the same thing, except in the latter you can sort of tell the car when to shift (I say sort of because the car can take over and shift when it wants to keep you from damaging it). D/S is similar to "sport" mode, the car will try to shift at a higher RPM. The manual automatic shifting allows you to choose higher shift points but is not necessarily "sport" mode because you can still choose to shift at 2000rpm and not 6000rpm. So really the point where you choose to shift (for maximum acceleration) should be based on peak torque and HP output. Not sure exactly what RPM that is on the '07 530i. The D/S should usually choose a good shift point if you're flooring it, but things like hills and turns can throw that off.



A side note, the 6spd auto transmission has hill assist in which case it locks up the transmission on inclines to prevent roll back. So I would advise you not to add throttle and brake on any sort of an incline because it would likely add unnecessary wear to the tranny.

smcd

Oh please, this is a BMW, not an Oldsmobile. If the car is sufficiently warmed up (driving for a few minutes), I would not hesitate to floor it and keep it floored through 1/2/3 as needed. The mileage will stink but it's a heck of a lot more fun.

Keep in mind that BMW places the redline where it conservatively knows the internal systems can run again and again. A more concerning red-line would be 1,000 rpm higher than OEM.

MRV99

you will not be able to over rev the engine in manual mode becasue the rev limiter will kick in and the car will shift. Unless you have the Sport transmission(with button and paddle shifters), I don't think you will be able to shift faster than the automatic trans.

550nyc

Am not sure about the automatic one, But on the SMG i had to replace the clutch and fly wheel after launching off the line a couple of times and switching gears at 6000 rpms

Bdaddylo

Hill assist uses the brakes and not the transmission.