Here’s my creation:
It was intended as a Batmobile but I have neither a Batman nor a Robin minifigure so I substituted in an alien figure from Space Police. My main thought while building was that I wanted it to be sturdy, so used a 6×8 technic frame for the sub-carriage (in general one large Lego® brick is much stronger than two bricks attached together). To the 6×8 technic frame I clipped x15 technic beams to carry the wheels:
The mobile has flick missiles, levers and control panels, and exhaust valves in back (Imagine giant flames shooting from them).
Running it along the ground shows that it drives almost perfectly strait.
I hope you enjoyed learning how I built my Batmobile!