­­No ­matter what kind of car you drive, you'd probably love to get better gas mileage. Even if you drive an efficient hybrid vehicle, each time you fill the tank you may find yourself thinking, "Wouldn't it be great if I could get even more mileage? Like, more than 100 miles per gallon (42.5 kilometers per liter)?" Well, if a group of visionary engineers have their way, you just might.

People like energy policy expert Amory Lovins, designers at a company called Fiberforge and even automotive engineers at Volkswagen have been hard at work trying to create cars that are incredibly light and ultra efficient. The result: hypercars. With advanced materials and alternative fuel systems, hypercars don't have to sacrifice safety, performance or luxury in the name of fuel efficiency.

If you think automotive technology is ready to evolve after staying basically the same for the last 50 years, then this article will explain why you might be right. Instead of steel-framed multi-ton vehicles powered by internal combustion engines, we're going to show you cars made of carbon-composite materials that are lighter and stronger than steel, with sleek aerodynamic shapes and incredibly efficient engines. In fact, some of these cars are so efficient that you could plug them in and return power to the grid for a discount on your electric bill. This isn't just pie in the sky futurism, either. We'll show you some hypercars that are on the road today.

If you're planning to design a super-efficient car, the first thing you need to do is figure out what makes the vehicles currently on the road so inefficient -- it turns out to be a pretty long list. Find out what tops the list on the next page.