So ive been told that the lowest rpm at highest gear will give best mpg. I dont want to work my motor at 1000rpm tho. What rpm is best for mpg without possibly hurting engine life?

 

i assume your car is a m6? shift as early as you can without bogging the engine, pretty simple really. Usually i end up cruising around 1300-1500 in 6th gear on the highway, even in town when cruising you can keep it that low.

 

it feels like it lags alot at 1500rpm tho,, that wont hurt the motor?

 

I have a gauge somewhat like this one, that I put in a previous car many years ago. It's a vacuum gauge, and works off the principle of how your throttle position affects your engine vacuum. It's a fairly accurate relationship (throttle position, vacuum, and engine load), and it gives you something to watch and be conscious about. MPG isn't only about your rpm's, it's also about where you have your right foot planted to hold those rpm's.

 

hows the install on something like that? I also am still wondering what too low of rpm is.

 

The gauge hooks up to any manifold vacuum source. Use a T fitting if you're tapping into an existing hose. If you can feel the engine chugging in a higher gear, drop it down one. Too high a gear (straining the engine) can affect gas mileage just like too low a gear can.

 

Your not going to hurt your motor from running at low an RPM. Worst case is you run a little higher cylinder pressure then you would if you down shifted but even that would be nowhere near the cylinder pressure you would have at wide open throttle. Everything Camaro 69 said is dead on. Higher vacuum is a good indicator that the motor is working less. Everyone should have to drive a car with a MPG gage in to see how much how you drive effects MPG. Its nice on the newer cars you and turn them off because after a few weeks you don’t need them anymore. You can tell by feel how to drive for the best mileage.

 

ok, thankyou! when i scrap together 30bucks ill throw one in

 

I keep it between 1500-2000 in 1st through 5th but go as low as 1200-1300 while in 6th.

 

Sweet, I want.