[eshoukry93]

So after filling up my car every week because I've been ecstatic about my 335i, I'm ready to settle down and get some good gas mileage out of my car.

I have a 6mt e92 335i and was wondering what were your recommendations for driving stick for better fuel economy?

What rpm's or speed are you guys changing gears? Is there a general rule for changing gears? I've heard 3k rpm is a good point but I'm really looking to get the best fuel economy out of my car when I'm not trying to make it purr.

Thanks for the advice.

ps. Please no comments about I should have bought a geo if I wanted good gas mileage.

[AndreyATC]

keep it under 2K rpms most of the time (2k is shifting point)
roll on neutral where you can
slowly accelerate from the stop

using all that gave me 37.8mpg on my 330ci on freeway and 26+ mixed

[nj335i]

I think shifting at 3k RPMs is decent... at 2k RPMs, it seems like you'd be bogging your engine alot.

[HyperM3]

Originally Posted by nj335i

I think shifting at 3k RPMs is decent... at 2k RPMs, it seems like you'd be bogging your engine alot.

+1. I dont know how anyone shifts at 2. I keep mine shifted at 3k. Plus if you think about it, you have to press the gas pedal harder at 2k in a gear up to get the car moving faster than you would in the previous gear at 3k. Taking that into consideration youre now using more gas.

Its like on a bike. You can put it in a higher gear but you have to exert more force(gas) to get the bike moving faster(or at all). Its better to keep it in a lower gear until youre at a speed where you can be steady at then put in a higher gear to keep the revs low.

Just my opinion.

[AndreyATC]

Originally Posted by nj335i

I think shifting at 3k RPMs is decent... at 2k RPMs, it seems like you'd be bogging your engine alot.

This monster has max torque @ 1500
With 3K your mpg will drop big time

[dmboone25]

I agree that 3K is probably best--slow acceleration is probably the biggest factor, taking off slowly should really help out your MPG.

[AndreyATC]

Originally Posted by HyperM3

+1. I dont know how anyone shifts at 2. I keep mine shifted at 3k. Plus if you think about it, you have to press the gas pedal harder at 2k in a gear up to get the car moving faster than you would in the previous gear at 3k. Taking that into consideration youre now using more gas.

Its like on a bike. You can put it in a higher gear but you have to exert more force(gas) to get the bike moving faster(or at all). Its better to keep it in a lower gear until youre at a speed where you can be steady at then put in a higher gear to keep the revs low.

Just my opinion.

My friend thought the same thing with his 330i and he never got even remotely close to my mpg #s
To each his own

[HyperM3]

Originally Posted by AndreyATC

This monster has max torque @ 1500
With 3K your mpg will drop big time

Thats at WOT. Who the hell drives WOT all the time to conserve gas? I think the statement that your mpg will drop "big time" is unlikely. This car will move just as easily without getting on boost and you can save gas. We arent suggesting shifting at 5k, 3k is a safe point where you arent stressing the engine much to push it. 2k is silly, its just barely above idle(not really but close).

[johnc_22]

I can't get a smooth shift from 1-->2 or 2-->3 if I'm at 2K. I usually shift at 3-3.5, especially when the car is cold. Is this a CDV thing?

That said better gas mileage would be good but then I'm still under 2K miles on the car so I'm sure it will improve.

[HyperM3]

How about this to the OP. Drive different styles for a couple tankfulls. Try to drive the same routes all the time, if you commute that makes it easier. Dont take any long distance trips to find out. After a couple tankfulls, youll find what works best for you.

Im getting between 17-19mpg right now because my commute is completely stuck in traffic. I HIGHLY doubt shifting at 2k instead of 3k is going to make my mpg magically improve. On top of that, Its not when you shift that really saves gas, its how hard into boost you get that sucks it down.

[AU335]

Originally Posted by johnc_22

I can't get a smooth shift from 1-->2 or 2-->3 if I'm at 2K. I usually shift at 3-3.5, especially when the car is cold. Is this a CDV thing?

That said better gas mileage would be good but then I'm still under 2K miles on the car so I'm sure it will improve.

+1 I think the CDV mod will help with that. I am installing mine later this week...hopefully it will help with the 1->2 shift

[danimal]

Actually, the lower RPMs you can shift without bogging the engine, the better. Medium to even high throttle (though probably not WOT), doesn't hurt mileage as it lessens the time you spend accelerating (which is when you use the most gas). Bottom line: revs are the enemy, not throttle opening.

[HyperM3]

Originally Posted by danimal

Bottom line: revs are the enemy, not throttle opening.

So If Im firmly pressed on the gas(maybe 4-5lbs boost) from a standing start(500rpm) and shift at 2k Im not using any more gas because Im still shifting at 2k? That doesnt make sense considering I can drive in vacuum (-02.to -00) and still accelerate but shift at 2k(obviously not as fast). However, if Im doing that and I shift to 2nd at 2k then I get into boost trying to get up to speed again. However, I could still shift at 3k without getting into boost and shift into 2nd but be in a higher powerband where I can still stay in vacuum and accelerate. The second I see my boost gauage go over that 0.0 mark, I know my fuel is going somewhere faster than not and it has no care where Im shifting.

[achien]

Driving "normally" on a flat surface, I usually shift between 2,500 - 3,000 RPM on other non-turbo cars.

For the 335i, I keep it between 2,000 - 2,500 RPM on "normal" driving. Once both turbo kicks in full-force (~2,300 RPM on my car), you are simply burning "cash".

The above scenario is for "flat" surface only, actual RPMs between "shifts" could be higher or lower depend on whether you are accelerating uphill or rolling downhill.

[STE92VE]

IMHO, I drive without regard to gas mileage but more to circumstance. If I'm in stop and go traffic or just running local errands, I will shift at a lower RPM point than if I am doing spirited driving like getting onto the highway or having some fun on the twisties. No need to clutter the mind with 'what kind of gas mileage am I getting' when I'm enjoying the Ultimate Driving Machine.

[montreal_bimmer]

i would go with gradual acceleration and shifting at 3000rpms, and coasting as much as possible

[HyperM3]

Who am I kidding, I live in the state with the cheapest gas(just got 93 for $2.99 yesterday). Im in it to win it. What do I care if I save 2mpg.

[Wile E.]

Originally Posted by achien

Driving "normally" on a flat surface, I usually shift between 2,500 - 3,000 RPM on other non-turbo cars.

For the 335i, I keep it between 2,000 - 2,500 RPM on "normal" driving. Once the second turbo kicks in full-force (~2,300 RPM on my car), you are simply burning "cash".

The above scenario is for "flat" surface only, actual RPMs between "shifts" could be higher or lower depend on whether you are accelerating uphill or rolling downhill.

I believe our 335i's both turbos are in acting in parallel, not sequential. There is no "second turbo" kicking in.

[PiperD]

^^^ +1

I think that's the second time I've seen that from Achien.

Anyhow, FWIW I shift at 3-3.5k on the 1-2 shift, then 2.5-3k on the 2-3 shift, and tend to shift at around 2k in subsequent gears.

This depends on the road incline and speed limit, traffic, etc.

[danimal]

Originally Posted by HyperM3

So If Im firmly pressed on the gas(maybe 4-5lbs boost) from a standing start(500rpm) and shift at 2k Im not using any more gas because Im still shifting at 2k? That doesnt make sense...

I'm not sure if the low revs/high throttle advice applies to turbos (staying out of boost may be the more important consideration).

In any case, you might find this interesting:

Road & Track - Technical Correspondence, November 2005

-Dan

[Safety2213]

Take the bus! I have found that I burn a lot of extra fuel by speeding up and slowing down on the freeway. Speeding up to pass a car and then eventually hitting traffic to find the guy right next to me. (Don't you hate when that happens). Anyway, I think saving gas is all about keeping constant speed rather than shifting points.

[achien]

Originally Posted by Wile E.

I believe our 335i's both turbos are in acting in parallel, not sequential. There is no "second turbo" kicking in.

You are right, it should be Parallel Twin-Turbo...

^^^ +1

I think that's the second time I've seen that from Achien.

Anyhow, FWIW I shift at 3-3.5k on the 1-2 shift, then 2.5-3k on the 2-3 shift, and tend to shift at around 2k in subsequent gears.

This depends on the road incline and speed limit, traffic, etc.

Guess I am still stuck in the 90's, good old Sequential Twin-turbo, how I missed them (and the turbo lag too)...