By Cat DiStasio
Fuel efficiency is one rating that can really set a car apart from the pack. Although you can't yet walk into just any dealership and drive away in a vehicle that gets more than 100 miles a gallon, there are some sweet rides out there that demonstrate just how incredibly efficient a car can be. To get a better idea of what the uber-efficient car of tomorrow looks like, we've compiled some of the most efficient vehicles on the planet, all of which exceed that 100-mpg marker. In fact, most of the cars featured here leave that rating in the dust, and several break into the quadruple digits.