Need advices for manual shifting mode.

[iamjona]

I've a M35'06 for 2 months already, so far I get very bad MPG (60% City/40% Free Way) 12.8-13.4MPG. I don't think the car is the problem, because I see in the log that the previous owner always get around 20-25mpg. Someone suggest me that I should use manual mode so that I can get better MPG, but I don't even know how to drive manual in the first place so I have no idea which RPM should I shift gear and will manual mode cause a transmission problem in the long run or not? well Please give me some advices

Thank You

[AlbuquerqueM45sport]

Check your air cleaner, and remember that lot's of stop and go traffic will affect your MPG. This is a performance vehicle not an econo-box. Don't expect much improvement over 17mpg. You might consider a Civic or similar vehicle for high MPG, vs. performance.

[palincal]

Manual mode won't increase your MPG much. I have driven manually for a couple of tanks and didn't see any difference. Check your tire pressure too.

You can shift the gears based on the sound of the engine or the RPM. Since M is a very refined car, it may not be very intuitive to depend on engine sound. You can shift based on the speed of the car too. To maximize MPG, shift to 2 and 3 together as soon as you start off (5 MPH). Shift to 4 at abt 30 and then shift to 5 at 35. Let the car downshift on its own to maximize coasting.

BTW, the manual mode is hardly manual in this car. The downshifts happen automatically and the upshifts don't happen if the correct RMP or speed has not reached. Overall it is a pain to drive in manual mode with this car.

[humblepie]

I have a 12k miles 2008 m35 and I find that whether I'm in manual mode or auto, it doesn't help that much maybe 1-2MPG. It's more for acceleration control than gaining more MPG. Plus, for an average driver accustomed to an auto trans like yourself, the auto mode will prob shift to the higher gears faster than you would in manual mode, so you'd save more gas in auto mode.

I haven't driven a car w/ a v6 engine before and I found I had to change my driving habits a bit for this car. For local street driving, from a stopped position, what I tend to do is accelerate at a moderate if not semi-aggressive rate . Then when I reach the speed I desire (or the speed limit), I try to depress the gas to a bare minimum. By bare min, I mean just slightly enough gas such that the RPM of the engine is above what it would normally be at if you don't have the gas pedal depressed at all (aka let go of the gas completely).

You can check the difference in RPMs that I'm alluding to by letting go of the gas after you reach your desired speed and noticing how low your RPM drops, but by depressing the gas pedal just slightly you can keep the engine running at the bare min RPM, which will maintain the forward momentum (unless you're on an incline). So on a typical flat road, @ 25-35 mph, I'd probably have 1200-1300 RPM w/ the gas off and 1600-2000 RPM for the bare min RPM.

Later on if you get used to this, then you can double check how sensitive the gas pedal to engine RPM ratio really is by checking your fuel economy estimator. I noticed that even though I think I'm not depressing the gas pedal too much, I can let go of the gas even further but still maintain forward momentum. This is much more evident while driving on the highway.

Of course, you wont get much fun factor from your car if you drive this way too often, but for those conservative days, I found this is the best way to conserve gas on the m35.

Either way, I found my best combined MPG was around 22 and my avg is 19.

For pure local street driving, it can dip into the 15-16 range.