Very nice set up! Mine is similar but only have 2 suction cups on the hood. This isn't mine but it's the exact same set up.
And one of my photos:
I cheap way to do not full frame car shots but have the rig look with the wheels is have someone drive the car slowly while you hold your tripod full extended against the car and take a long exposure. Same as a rig but won't have the full car in it, still fun do with wheels and such though.