Hi, I'm trying to program a sort of small car simulator, but I have a problem. I managed to calculate the force on the car, acceleration, speed, air ressistance etc... My theory: We've got a car at a certain speed (v) and I calculate the RPM: Code (Text): rpm = ( v * gear-ratio * current gear ratio ) / ( 2pi * tyre_radius) * 60 Now I calculate the torque: Also I calculate the engine power (Watt) from horsepower. Code (Text): torque = ( horsepower * 745.69987158227022 ) / ( 2pi * (rpm / 60 ) ) Then I am able to calculate the force on the car: Code (Text): F = ( torque * final_gear_ratio * current_gear_ratio) / tyre_radius Remarks: 1. it doesn't work when speed = 0 2. it's better to work with a torque and power function because they aren't the same at different engine speeds (max power at certain RPM), but how do you create/calculate such a function. Or can this only be made by testing the engine to get the values? example of one: http://www.electroprivod.ru/theory/2-8.gif I'm from Belgium so please use the SI units!