Another idea I had while playing RoR and BeamNG is that when you are inside the car it sounds exactly the same as if you were outside it. It sounds a lot different when you are outside next to the hood than inside behind the wheel. Not only inside is the engine more muffled but also inside you can hear the key dinging noise when you start the engine. For example, in the newer Ford pickup trucks, you can hear the familiar ding-dong tune when you insert the key.
