I just came back from a road trip and got about 450 miles per tank!!!...I noticed that for most of the trip the rpm was just under 3000. Therotically, shouldn't I be able to achieve that same gas mileage in the city if I keep the rpm under 3000?

 

Well, city is more stop and go... but if you were to go the same route (highway or traveling) and the same amount of trucks in front of you then you should be able to go the same amount of miles.

A lot of factors could play into this situation here...

 

ur cruising at under 3 k as opposed to bringing the car up to 3 k rpms in the city, in the city if u cut the rpms in half to like 1.5k u'd get that kind of gas mileage, trust me on that one

 

here's is something i have been wondering about:

Do you get better gas mileage going down a hill in neutral or keeping it in gear? (5- speed)

Also, do you get good/bad gas based on how you depress the accelerator? (as in riding in 4th gear with the pedal depressed a ceratin amount as apposed to 5th gear at the same depression)---( if there is a difference would it be just better gas mileage in 5th gear because the engine is not turning over as fast?

 

keeping it in 5th or neutral should net the same MPG as long as ur coasting and not accelerating down the hill. i think if ur going say 30 mph and ur in 4th, u'd get the same mileage as if u were doing 40ish in 5th, but the amount of depression on the accelerator definately would make a difference, in my opinion, however that is a tough q to answer, it is absolutely possible to get the same MPG in 4th and 5th? i think yes because i think MPG is very much determined by the amount and speed the accelerator is depressed... anyways i know that makes no sense so good luck finding answers to that NissanSE98 lol

 

Gas mileage does have some to do with RPM...but more with throttle position. If you were to look at a fuel/air map you would see that the greater the throttle opening, the more airflow and therefore, more fuel flow.

I would say RPM does matter as well too...but not as much. If you were doing 2000 RPM that fuel injector has to inject fuel 1000 times per minute. Where 3000 RPM, the fuel injector is doing 1500 times per minute. So it should be using a little more fuel at a higher RPM.