When GMC unveiled their Granite concept vehicle, one of the key design elements was the tough little SUV's reconfigurable seats. When not hauling four friends, the passenger seats flip in towards the center console, creating a storage space "large enough for a mountain bike." Guess that's true as long as you don't mind chainring stains on the door panel or a handlebar in the ear.

GMC calls the look "progressive industrial design" for the ultimate city ride.

The Ganite's interior before making way for your mountain bike.

Load it up. Your bike as your passenger. Looks like Photoshop might help get the bike to fit.
Full information on the GMC Granite Concept.