4. Flying Cars
These are definitely overdue by a decade or so. We thought entering the new millennium meant that the combination of airplanes and automobiles would soon hit the shelves. Even though Michelin and Goodyear might suffer a loss in business — not to mention finding a replacement for rims as a way to stunt — obeying the laws of the road would be so much easier if the sky was literally the limit. The only issue we could see people facing is choosing between a flying Ferrari, Learjet Lexus, or aero Audi. Shouldn’t be too hard, right?