[Brett]

Lately I have hit more stop & go traffic here in DC and have found my commuting mileage dropping from the mid-to-high 50's to the mid-to-high 40's. I know there's only so much you can do to keep mileage up in stop & go, but I was wondering if it is better to keep the car in lower gear for longer in these situations (feathering it to maintain speed) rather than shifting to 3rd as quickly as possible and then flooring the pedal to have the assist kick in. The car responds much better in the first situation, but I'm trying to get the best mileage. Generally speaking, how high should the rpm's be when driving around in city conditions - 1k-2k, or 2k-3k?

 

[Armin]

I try to keep rpm's low. Speed up quickly (ussing assist) and then coast. Try to enter auto-stop and coast with the engine off as much as possible. In extreme stop-and-go, wait until there are several car-lengths space before starting the engine again. Yes, once in a while you get someone in his tank who thinks he needs to jump into that space, but oh well...

 

[Tim Maddux]

I used to city drive my 5spd like I did on the highway; accelerate hard and then cruise at moderate speeds. I have improved my city mileage by accelerating more gradually. Also, look into coasting rather than feathering when in gear. If you need to maintain speed, you should still shift up as high as you can ... but not so high that your car can't maintain speed in lean-burn mode. For example, I often see my upshift light when I'm going along in 3rd gear but I know that going into 4th or 5th will cause me to slow down and eventually drop out of lean burn.

 

[Brett]

Coasting v. Feathering

In other words, keep it in a lower gear for longer and maintain speed by touching the gas pedal every so often (keeping my foot completely off in between in order to coast)? RPMs would be between 2k-3k in this situation, correct?

 

[Armin]

Re: Coasting v. Feathering

RPMs would be between 2k-3k in this situation, correct?

That sounds like way too much rpm, especially when you don't need power!

I'd say 1.5k to 2k while accelerating, but then either shift up if there is enough room to continue at constant speed (at 1200 to 1500 rpm), or use idle-stop to coast with the engine off.

 

[Tim Maddux]

Re: Coasting v. Feathering

In other words, keep it in a lower gear for longer and maintain speed by touching the gas pedal every so often (keeping my foot completely off in between in order to coast)? RPMs would be between 2k-3k in this situation, correct?

As high a gear as possible without lugging the engine. By "coast" I mean let the engine idle in neutral; if you take your foot off the gas in a low gear then fuel-cutoff will engage and the engine drag coupled with regen will slow you down too much.

 

[james]

When I try to accelerate in too high a gear, I seem to get really bad MPG, and at best minimal acceleration. I tend to use 2-5 myself: accelerate briskly in 2nd (and 1st if from a stop) to desired speed, then drift along in 5th with just a touch of throttle to keep the speed up.

I believe coasting in neutral will actually waste gas (unless you're in idle stop). If you leave it in 5th with minimal throttle, you're getting a little something out of the gas that's burned (or you get into idle cutoff), or are getting some regen. Coasting, whatever gas is burned is burned to no effect at all.

 

[Guest]

I am accelerating up to 2500-3000 rpm in 1st & 2nd, then shortshifting 3rd,4th into fifth. Occasionaly using upto 6000rpm in 2nd to overtake :twisted:

I am crusing at about 80mph on motorway, still managed to get 75mpg & charge never gets below 1/2 full.

 

[Will M]

I work to get my city mileage up to about 60mpg in good weather. Instead of holding to some principle of keeping low rpms or not idling while coasting, I just look at the mpg meter and do what it tells me to do. Sometimes a lower gear gives me higher mpg than a higher one. I don't know why. It just does. So, under those conditions, I drive the lower gear.

I also coast a lot, often with the engine running. You can talk about all the wasted energy you like. The mpg meter pegs out at 150 while I'm doing this.

Note that I do live among hills. Deciding between coasting or fuel-cut mode for me is usually a matter of managing my speed. If the hill is long and steep, I use fuel cut mode to charge the battery and hold my speed down without braking nearly as much, if at all. If the hill is slight, I'll coast in neutral so long as that gives me a reasonable speed for driving conditions.

Traffic and safety are more important than mpg, but the mpg meter will teach you a lot more about saving gas than any overriding principles of running top gear/low rpms or irrational theories about how an idling engine is wasting energy. If that idling engine is burning less gas than an engaged engine would under the same conditions, idle away.