3 Cars Win 100 MPG Race

The X-prize Foundation showcases and rewards cutting-edge innovations in fields that have the potential to benefit humanity.

The Automotive X-prize is for fuel efficiency. Sponsored by the Progressive insurance company and partially funded by the Department of Energy, it was given in three different vehicle classes. Regardless of the class, the cars had to be safe, "commercially viable" -- meaning only that they had to perform more-or-less like a regular cars -- and they had to get at least 100 miles per gallon or the equivalent.

MORE AT CNNMONEY.COM

» A first look at Chrysler's new 2011 lineup

The contest was launched in 2008. Beginning this summer, the 136 vehicles that entered -- representing 111 teams from around the world -- were winnowed down through a serious of tests. Besides fuel economy, cars were also tested for things like acceleration, braking, handling and maneuverability.

In the "Mainstream" class, which offered the biggest cash prize, vehicles were required to have four wheels, seat four people and have a driving range of at least 200 miles. In other words, they had to offer the bare basics of a typical car.

Team from: Lynchburg, Va.

Class: Mainstream

Prize: $5 million

Fuel: E85 ethanol

Fuel economy: 102.5 MPG

Edison2, a team that fielded entries in all three classes, used a small internal combustion engine rather an electric motor or hybrid power. The car relied largely on its light weight -- no heavy batteries -- and its best-in-class aerodynamics to win the prize

Team from: Winterthur, Switzerland

Class: Tandem

Prize: $2.5 million

Fuel: Electricity

Fuel economy: 205.3 MPGe

Cars in the "tandem class" were two-seaters with the occupants sitting one behind the other. In this case, you might question the use of the word "car" since this vehicle looks an awful lot like a motorcycle. It does have four wheels, though. It's just that two of them fold up and out of the way while driving, dropping down at low speeds to provide stability. It thus qualifies as a car under the X-prize rules.

Its bike-style body saves a lot of weight, which confers advantages in both efficiency and performance. In tests, this car got to sixty miles per hour in a relatively blistering 6.6 seconds.

Team from: Mooresville, N.C.

Class: Side-by-Side

Prize: $2.5 million

Fuel: Electricity

Fuel economy: 187 MPGe

Li-ion Motors Corp.'s Wave II

Vehicles in this category seated two people side-by-side, as the name implies. They also had to go at least 100 miles before needing to refuel or recharge.

The winner, in this case, drew on the advantage of electric motors: their much greater efficiency compared to internal combustion engines. Electric motors turn nearly all the energy fed into them into motion. Gasoline engines turn only about 30% of gasoline's energy into motion while most ends up wasted as heat.

This car got 187 MPGe, or miles per gallon equivalent. In other words, it can go 187 miles on same amount of energy as that contained in one gallon of gasoline.

This Wave II also minimized one big disadvantage of electric drive: weight. Gasoline contains much more energy per cubic foot than batteries, so electric car batteries end up being big and heavy compared to a tank of gasoline. In this case, the car itself, built largely from aluminum, is so light that it all adds up to only 2,176 pounds total. That's less than a tiny Smart car.

Still, the Wave II takes almost 15 seconds to reach 60 miles an hour, good enough to win here but downright pokey by most standards.