Can an insect fly as fast as a car?

When you're driving at let's say 100 mph, and you have a fly buzzing around in your car, does he get thrown to the back window because you are travelling faster than him or is he free to fly around the car? He's not actually in contact with the vehcile itself as he's flying around. So would the fact that the car is creating a sort of 'enclosed space' enable the fly to be free from g-force? How come we can feel it when we're in the car then? And if we were able to float around without touching the seats or any part of the car, would the vehicles speed mean nothing to us aswell?