There are two things I have to suggest here; First of all I think it would be nice if the turn signals had noises like they do in actual vehicles. That clicking noise your turn signals make when they blink, you know? Secondly I would like maybe a little brake noise, like a little sound where you hear a little pumping sound to imitate the sound of the brake fluid taking action and a little bit of a brake squeak depending on how damaged the vehicle is. Just a suggestion!
A sound overhaul is on the todo list but fixing bugs, creating content and gameplay are first in line in the devs' agendas. Don't worry, they'll get there just probably not that soon.