Though it would seem best to drive in such a wat as to minamise your cars revs, that would entail changing up gear as rapidly as possible, but changing gear seems to have a negative effect on milage. So what is the best way to drive a manual car in order to get the most milage from your gas?
Downhill. Clutch disengaged making gear selection moot.
Get to the highest gear as quickly as possible. By that I don’t mean go 0-60 in 4 seconds, but don’t linger in the lower gears any more than you have to. If you have a shift light, follow it. If you don’t, shift around 2500 RPMs. You won’t get max performance, but that should be enough for you to get into the next gear without bogging down. When decelerating, stick to the brakes. I was taught engine braking and it works well, but using the engine to slow you down raises the revs and puts wear and tear on your clutch. Brakes are comparatively cheap.
Basically, the less interaction you have with the engine the better on your gas mileage. It’s not a very satisfactory way of driving, but it’s easier on gas so it can be a satisfactory tradeoff.
I’ve heard that the best way to accellerate is to do it fairly quickly, but not to over-do it. Kind of a judgement call, I think. As far as driving itself goes, the best thing to do is to plan ahead. (This also increases safety, BTW.) Rather than make abrupt changes in speed, try to maintain a constant speed. By planning ahead you can ease off the accellerator and slow down gradually to save fuel. Energy is ‘lost’ when you use the brakes. That is, you’ve expended energy to get up to speed. When you apply the brakes, kinetic energy is converted to heat. So basically you’re running your brakes on the gas you used to get up to speed. By planning ahead, you can avoid expending generating this heat energy by not having to use the brakes as much.
I’ve complained that up here people tend to drive 5 mph below the speed limit, not matter what the speed limit is. I’ve quipped that I drive in fear of coming to a 5 mph zone and being stuck behind people who are stopped. But you can save gas by driving more slowly on the freeway. (On surface streets – near my home the main road is four miles long and has a 50 mph speed limit and only two stop signs – try not to go too slow. Below a certain speed your mileage drops.) So I’ve taken to driving more slowly on the freeway. At 70 mph I’m lucky to average (i.e., when taking in-town driving into account) 19 mpg. It’s usually closer to 18. By slowing down to 60 or 65 (depending on traffic) I average over 20 mpg. When I lived in L.A., which has a lot of lanes on the freeway, I got up to 25 mph in my Cherokee by driving 55 mph in the slow lane.
When I’ve looked up the manufacturer’s recommendations for the best (i.e. most economical) speeds to change gears (often listed somewhere in the documentation), they always seem to be quite high, keeping the revs up. And this seems to make more sense to me than Airman Doors’ suggestion, which surely just means you have to be using far more accelerator after each shift?
When I had my 87-horse 1993 Escort I could run it effortlessly at no more than 2500 RPMs (the shift light would come on as well). Some cars may differ, and it’s really more of a feel thing.
Don’t change up too soon or you’ll end up doing 2000rpm in fifth with your foot flat to the floor not going very far! Modern (eg. the 16 valve ones) don’t have much torque at low revs so you’ll be better off revving a bit higher in 3rd then doing a quick change from 4th to 5th and cruise.
Also, modern engines use pretty much no fuel when you lift off the accelerator coasting to a stop / slowing down so lifting off a bit earlier will help compared to braking sharply when you want to slow down.