You need a long acceleration sound which goes from stopped to top speed, and when the player pushes the gas, you start playing this sound from the right point.
When they reach the max acceleration, you switch to a looped sound of max acceleration.
When they let off the gas, you have a second long sound of deceleration, from max speed to stopped, which you start playing at the right point.
And when the car has come to a stop, you play the idle sound.
It's pretty simple, cause the player is either accelerating at a constant speed, or decelerating at a constant speed. It would probably be more complicated to do on a console with analog control of the accelerator. In that case you might have to have a few different acceleration sounds for different speeds of acceleration and properly transition between them with pitch bending and fades or something, and use small segments for looping when the player holds the accelerator at a certain point.
Play some Half Life 2 and see how they did the car sounds in that game. Unless I'm mistaken they've done exactly as I describe above.
When they reach the max acceleration, you switch to a looped sound of max acceleration.
When they let off the gas, you have a second long sound of deceleration, from max speed to stopped, which you start playing at the right point.
And when the car has come to a stop, you play the idle sound.
It's pretty simple, cause the player is either accelerating at a constant speed, or decelerating at a constant speed. It would probably be more complicated to do on a console with analog control of the accelerator. In that case you might have to have a few different acceleration sounds for different speeds of acceleration and properly transition between them with pitch bending and fades or something, and use small segments for looping when the player holds the accelerator at a certain point.
Play some Half Life 2 and see how they did the car sounds in that game. Unless I'm mistaken they've done exactly as I describe above.