Yeah, that is a cool video and I agree it was probably debuted at an Intl Auto Show in the mid/late 90's. Personally, I wonder what ever happened to the actual stage car from the movie "Mission To Mars"??? Perhaps, some movie executive has it.

With regards to a roof, an enclosed compartment folding hardtop would be ideal; if not, then a bolt-down "clam-shell" hardtop would suffice like those suspended from your garage ceiling (early Corvette style). However, the vehicle does need some sort of integral style roll-bar like the old convertible Shelby Mustangs from the late 60's.