no tanks under 40 MPG in a year

[rningonfumes]

Yes, 40-50 is the magical number for most cars, 45 for the Yaris. After that range, you start to battle wind resistance and the power needed after that begins to triple. So you need to accelerate (takes up power ) and then keep a constant pace, how fast the pace you want to keep the car at is how much more you will put in...

Note that the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power.

http://en.wikipedia.org/wiki/Drag_(physics) (go down to where where it talks about power)