AlexFW

I have recently bought a 545i with SMG. The car is great, DDC is way
cool, the comfort seats with the adjustable bolsters are great too,
everything is save for mileage (11.5mpg with half city/half highway)
but you can't have everything.
Now, I do have a matter I'd like to ask the forum's advice about: to
the best of my knowledge, the 645i has a more aggressive ECU map than
the 545 and I get the feeling that the same can be said about the SMG
settings. The gearbox is fast enough in Sport mode, but it doesn't
cut it with that disabled. So I was wondering, considering that AFAIK
there's a faster/sportier setting on the 6er and on the Z4, could I
upload that firmware on my gearbox? I mean, it's fine as it is, but
if it were possible, I'd love to do it.
If it is indeed possible, the problem becomes finding someone who can
do it reliably, either a BMW shop or a tuner. Any suggestions?

Thanks a lot!

realtyman

I think the only solution at this time is to always push the Sport button.

speedracerF4i

Alex,

getting 11.5 mpg with mixed driving condition is just wrong. I drive mine spiritely, and get 20 MPG.

When I have people in my car, especially my family, I usually prefer to have my tranny in normal mode. It's shifts are less violent.

znod

I have a steptronic. I am getting 15.6 with ave. MPH of about 28. Either of you or anyone else--what are your ave. MPHs (and MPGs for others)? I do mostly city driving obviously. I am a spirited driver too, but when not being spirited, I try to keep the instantaneous MPH on the high side.

znod

I doubt that the ECU maps and tranny settings differ between the 2 cars, but maybe. Of course, the HP and torque values from BMW are the same on the two cars--which provides a minor indication that the programming is the same. Also, BMW's performance figures for the cars are virutally the same--with the 645i being faster by a tiny margin--but it also is a tad lighter. Dinan supposedly is going to have some new parts for the 545i by the end of September--cold air intake, programming (maybe), exhaust, and MAF (maybe). If warranty is an issue to you, then I would not change the programming except via Dinan.

cobradav

The 6er rear end is also higher (numerically) than the 5 = trannys being equal.

SMG/Manual in 6er = 3.23; in 545 = 2.93
Auto: 6er = 3.46; 545 = 3.38

I am not so convinced that the ECU maps or SMG software are different but could be wrong. I think performance differences are weight & gearing related for the minor differences reported.

drjochen

I am sure this would not be that easy.
If someone could just reprogram the car so it remembers the Sport mode....

rodybmw

On my 545i SMG the lowest MPG that I have seen in 12000 miles of driving was 16.0. I always drive it in sport mode and with the AC on at least 6 months a year, quite a bit of city driving mixed with highway, and most of the time it is between 16.5 and 18.5 MPG.

Also, I have never heard of the 645's software being any different than the 545's. The slight weight savings and the higher rear end ratio more than account for the SLIGHT acceleration advantage.

drjochen

[quote name='rodybmw' date='Sep 15 2005, 08:49 PM']
On my 545i SMG the lowest MPG that I have seen in 12000 miles of driving was 16.0. I always drive it in sport mode and with the AC on at least 6 months a year, quite a bit of city driving mixed with highway, and most of the time it is between 16.5 and 18.5 MPG.

Your numbers are very close to mine. Ever if I push my car, I still get better than 14 mpg.

znod

My impression was that the rear ends for the 645i and 545i are the same--at least in the step transmission. As I recall, I checked this out on the BMW NA site when considering which car to buy. Currently, I can find no pertiinent 650i data for the same comparisons for the 650i and the 550i (same as 545i) on the BMW NA site. I am going to presume you are correct until we find differently. What you say is the best way to account for the small performance differences--a better explanation than the very small difference in weight.