Skip to Content

Ethanol-Powered Car Wins the Automotive X-Prize

A vehicle powered by an internal combustion engine beats electric cars to the $10 million competition.
September 16, 2010

Electric vehicles and plug-in hybrids have been enjoying the limelight recently as leading candidates for the energy efficient cars of the future, but a car powered by an internal combustion engine just rolled away with the top prize in the Automotive X-Prize. This contest has seen teams race vehicles that achieve the at least the equivalent of 100 miles per gallon of gasoline (MPGe) (under prescribed driving conditions), and that pass U.S. emissions and safety standards.

On Thursday, the Edison2 team won the $5 million prize in the “mainstream” vehicle class, which required the car to transport four passengers and to have at least a 200-mile range. The team’s car achieved 102 MPGe. The mile-per-gallon equivalent figure is a way to compare the efficiency of cars that use different kinds of fuels or energy sources, in a competition that included cars powered by natural gas, ethanol, gasoline, diesel, and energy stored in batteries. It’s calculated by determining how far the car travelled and how much energy it consumed relative to the energy content of a gallon of gasoline.

The team’s design formula was simple: make the car extremely light and aerodynamic, so that it can be powered by a small 250 cc, single-piston motorcycle engine. The winning car weighed 376 kilograms (830 pounds) and had a coefficient of drag of 0.15, far less than the Prius, which with a coefficient of drag of 0.25 is one of the best on the road today. Innovations included an aerodynamic body design like a diamond (rather than the rectangle base sedans have) that’s supposed to deflect other vehicles in the case of an accident, and lightweight wheels that project out from the sides of the car and serve to absorb impact in an accident.

Edison2’s winning vehicle.
The engine was also modified to run at high compression ratios (a measure of how much the fuel-air mixture is compressed). This allows more energy to be extracted from a given amount of fuel, but comes at the risk of engine knock (combustion at the wrong time in a combustion cycle). To avoid engine knock, the team’s engine runs on ethanol, which has a higher octane number than gasoline. The engine also re-circulates exhaust gases, a knock-reduction strategy that’s being used in some commercial engine designs, such as Ford’s EcoBoost engines.

The team started out expecting to design a hybrid car that could capture energy from braking using batteries and an electric motor. But it decided that the weight of the batteries and motor simply weren’t worth it.

While achieving 100 MPGe is a challenge, it’s not surprising that it was possible with a car that’s less than a third of the weight of a Prius. And if the car is to help make a dent in fuel consumption a lot of people will have to buy it. To address this, the prize was designed to ensure that the cars would have good performance: the winner had to win a race, not just achieve a certain mile-per-gallon figure. But the Edison2 car certainly looks strange and it doesn’t have much space inside it. Especially in the United States, where gas prices remain relatively inexpensive, it’s hard to imagine the masses rushing out to buy it.

Winners in two “alternative” categories were also announced on Thursday. In these categories the vehicles only needed to seat two people and have a 100 mile range. In the alternative vehicle class for tandem vehicles (where people sit one behind the other), the winning car was looks like a motorcycle with an aerodynamic enclosure for the passengers. During the award ceremony, it was announced that the vehicle achieved the equivalent of 187.6 miles per gallon, using batteries and an electric motor–a separate press release put the figure at 205 MPGe.

The winner of alternative class with passengers sitting side-by-side was Li-ion Motors, with a battery-powered car that looks like some sort of a green vegetable (but which President Obama’s science advisor John Holdren thought was quite good looking) and gets the equivalent of 187 mpg.

The MPGe figures for these battery powered vehicles are a little misleading, because they do not take into account the energy lost when the electricity is generated and transmitted. In the United States, the vehicles will do a good job offsetting oil consumption, since electricity isn’t generated using petroleum here. But if the power comes from a coal plant, it’s possible that the Edison2’s ethanol vehicle could result in fewer carbon dioxide emissions–especially if the ethanol comes from cellulosic sources such as grasses and corn stalks.

Keep Reading

Most Popular

Europe's AI Act concept
Europe's AI Act concept

A quick guide to the most important AI law you’ve never heard of

The European Union is planning new legislation aimed at curbing the worst harms associated with artificial intelligence.

Uber Autonomous Vehicles parked in a lot
Uber Autonomous Vehicles parked in a lot

It will soon be easy for self-driving cars to hide in plain sight. We shouldn’t let them.

If they ever hit our roads for real, other drivers need to know exactly what they are.

supermassive black hole at center of Milky Way
supermassive black hole at center of Milky Way

This is the first image of the black hole at the center of our galaxy

The stunning image was made possible by linking eight existing radio observatories across the globe.

transplant surgery
transplant surgery

The gene-edited pig heart given to a dying patient was infected with a pig virus

The first transplant of a genetically-modified pig heart into a human may have ended prematurely because of a well-known—and avoidable—risk.

Stay connected

Illustration by Rose WongIllustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.