Does overdrive make your car move faster?

Overdrive doesn't directly make your car move *faster* in terms of top speed. Instead, it makes your car move *faster* at a given engine speed, by reducing the engine's RPM at a given vehicle speed. This means that at a given speed, the engine is turning slower, potentially leading to:

* Better fuel economy: Lower RPMs generally mean better fuel efficiency.

* Quieter operation: Lower RPMs mean less engine noise.

* Reduced engine wear: Lower RPMs put less stress on the engine.

However, if you floor the accelerator in overdrive, the engine will speed up and your car will accelerate, eventually reaching its maximum speed (though perhaps slightly slower than it would in a lower gear). So, it doesn't *limit* top speed, but it changes the engine's behaviour at a given speed.