Not that I'm the end-all king of user interface (Actually I'm quite bad myself) but I have some areas of interest I feel that you should look into.
Constructive criticism, I promise.
1. Too much unused space.
2. What resolution are you writing this for? Does your application automatically resize everything based on what the end-user's resolution is?
3. Bad color scheme. Black + Bright-Green would be terrible for night-time driving. Possibly including either one theme that's fairly dark-toned, or having selectable daytime-nighttime skins.
That's all I can really comment on based on the main screen. Post up some other media screenshots and hopefully some more users will comment.