| Re: Lets lower speed limits because gas costs too much
Aerodynamic drag increases with the square of speed so small increases in speed generate large increases in drag. The difference in aerodynamic drag bewteen 55 MPH and 65 MPH is a rather shockingly large 39.66% Increasing speed from 55 to 65, however, does not mean your fuel consumption increases by 39.66%. The reason for that is the parasitic drag of all the moving parts in the drivetrain and the rolling resistance of the tires is using up much more energy than the aerodynamic drag.
The increase in drag from 55 to 75 MPH is 86%, nearly double
Your vehicle likely gets the best mileage at the lowest speed it can do in top gear, without lugging, and without slipping the torque converter. For most vehicles that's 45 to 55 MPH.
The engine's torque peak is where it has the best volumetric efficiency. This is NOT where the engine will get the best gas mileage since the only way to use peak VE, is to be at WOT. |