We did this show with our home school co op several years ago. Lucky for us, an area community theatre had just done it and we used their car. The car was built out of wood and put on two rolling platforms that were bolted together. The car was designed to look antique. That design helped make the squareness of the car be more aesthetically acceptable. The car had a hinged hood and secret compartment under. So girls could come out of the hood. We also put a dogger in there for when the car broke down and smoke poured out the hood. The roof was also sturdy enough to have Bobby dance on the top. Don't know if this helps.

I would love to see your design plans! There is no use re-inventing the wheel, so to speak! Thanks!

Sorry that I just saw your response. I don't always go to this list and don't seem to get notifications anymore. I'll send the designs to you today.