I love that you're taking time on the sound design. Not only does it let players know what the car is doing when not in sight. It also brings a lot more tension because you can hear it getting closer to you.
Yeah, sounds have a huge impact on both the gameplay and tension building.
It's interesting to make a horror game with cars as the 'monster', since everyone is fully aware of the way a car sounds and handles. Something I try to make good use of :D