I drive “easy” most of the time for the purpose of gas mileage savings by keeping the engine revolutions between 2000-2500rpms using the absolute maximum throttle I can get away with while keeping it in that range. There is a reasoning for this, low RPMs waste more energy as heat is evacuated from the engine, high rpms waste more energy as frictional loses increase, and the throttle plate is a WEAKNESS of the gasoline powered engine. Manufacturers are now starting to shy away from them in favor of variable valve lift in the cylinder head. The reason this is such a weakness is the same reason that you end up using a spoon rather than a straw for a thick milkshake, it’s just too hard to suck through! If a gas engine is left at idle with factory cams it generates in the area of 20psi of intake vacuum, that’s 20lbs of force per inch doing absolutely nothing and your engine still has to make it! The way I drive, my car gets in the area of 26-29mpg in the city and 37mpg on the highway, the EPA says my car should get 19/24 and back when I was 17 and floored it everywhere I got 17mpg.
If I had to make a car to set a conventional gas-powered economy record (or at least personal record it would be
- Drag Coefficient of .26 or less
- Minimal weight, 2000lbs or less
- Naturally aspirated 1.6L 4 cylinder
- 11:1+ Compression
- SOHC Solid roller valvetrain
- 5 speed manual transmission
It is my belief that such a car could be made to get 60+mpg without going overboard.