Car are in the air after Wheel Collide

Hey guys i have follow problem,i would make that the car can drive i make them Wheel collide but when i press the play button than it looks so :

http://www.imagebanana.com/view/qaq4mheg/screen.png

BTW: have anyone a script for a Control with the Arrow Key’s? that i can drive with it

does it have gravity? or another collider you did not notice?

thanks! it works great! i has delete it thank for your answer