Unveiled at the Frankfurt Motor show, the Porsche
918 Spyder can reach 60mph in less than 2.8 seconds, while BMW's futuristic i8
takes less than 4.4 seconds to reach the same speed.
But the sleek sports cars are designed to be fuel
efficient as well as fast. Porsche's Spyder can also do 72 miles per gallon and
is almost a third more fuel efficient than the Toyota's Prius, while the BMW i8
is even less thirsty as it can manage 113 miles per gallon.