Quote:
Originally Posted by swamp2
Good about gearing.
Still about shift times? Are you positive?
What about some evidence on the driving style to promote the best mpg? I am not trying to challenge you on this I am very genuinely interested and again I have heard the same exact argument. Doesn't it make a ton of sense that if your contention about how to best obtain mph in a meat machine/MT vehicle is valid then a very likely conclusion is that shift times must be a big part of the gain?
As far as skipping gears that really should not be a problem. Gear changes to the same shaft are likely to be slightly problematic (by that I simply mean about as fast as SMG) but any changes, up or down like 1<->4, 2<->5, 3<->6 and 4<->7 should be easily possible. It just mean a different synco is moved but all clutching and other operations are identical. For instance we do know already than in D1 the car acutally starts in 2nd gear, combine that with a skip right over to 5th and that seems like a good start to a lot better mpg. As well we know on the performance side that there is a multi-shift "kick down" shift pattern that will drop as many gears as required to obtain maximum acceleration. Whether or not BMW will offer gear skipping patterns specifically to obtain improvements to mpg is entirely another question. If all it took was another D mode option accessed by the Drivelogic mode lever/button I don't see why that would not be available. Hell call it the green or hippie tranmission setting! As long as guys like us get S5/S6 I can still hope for a D=hippie setting as well.
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As far as the best way to drive for maximum fuel economy..... The theory is that you consume less fuel by accelerating briskly (but not WOT) to your cruising speed rather than accelerating slowly to get to your crusing speed.
I did a search last night on some of the crazy people who are mpg freaks and found this:
http://www.crxmpg.com/accelmpg.html
Accelerating briskly will yield a ~3% improvement in fuel economy versus accelerating slowly.
As for the shift times, they matter for pure acceleration but for fuel economy, I don't think they matter at all (or at least it is noise).
If MDCT puts in a "Hairy Hippie Legs" mode and it shifts 1-3-5 then sure, this will be more efficient than 6MT. Short of a special alogrithm for fuel economy for MDCT, there should be no difference between MDCT and 6MT (save the gear ratios).