I think the most interesting new automobiles lately have been the multipurpose vehicles like the Envoy and the Avalanche. My concern is that higher fuel prices will make these vehicles unpopular.
But multipurpose vehicles don't have to be based on a SUV platform; a sporty 2-door hatchback coupe could easily transform into a small pickup truck with a 2-way hatch that either opens normally or slides forward to expose an open cargo bed. Another favorite idea is the minivan that converts into a pickup truck- I think this is an idea that would sell- it combines two of the most practical vehicle types into one vehicle.
I also like the idea of the interchangeable body modules that fit onto a variable-wheelbase front-wheel-drive chassis; after work, the driver removes the trunk pod from his 2-seat commuter car, extends the wheelbase, and affixes a pickup bed onto the frame behind the cabin. Or, van, sedan, convertible and other body styles could also be installed by adding or removing specially designed modules.
I can't help but notice how recent Cadillac styling seems reminescent of the Studebaker Avanti... which happens to be my all-time favorite car.
Studebaker also had the retractable station wagon roof... 45 years ago...