X Prize seeks the 100 mpg four-seater automobile

If you end up driving a 100-miles-per-gallon sedan in the next few years, you might be able to thank the Progressive Insurance Automotive X Prize.The contest has a $10 million prize for the company or team that builds vehicles that meet a series of criteria, including getting at least 100 miles to the gallon or its equivalent in other forms of energy.The prize has generated a lot of interest.

In January there were 50 entrants, then 60, and there are now 70 teams from 12 countries. Electric seems to be the leading contender at present.India's Tata Motors is the most recent entrant. An innovative company, they're the folks with the patent on the MDI compressed air car, and who this year announced plans to build the world's cheapest car, a $2,500 sedan called the Tata Nano.

They key to the new prize is that it will require some kind of technological leap. No production vehicle is currently anywhere close to meeting the X Prize requirements.Other standards, according to the X Prize draft guidelines, are these.The car needs to meet strict emissions standards, meaning it can't be energy-efficient but polluting. The limit is 200 grams of carbon dioxide per mile.

It needs to have at least four wheels and seat at least four people. (That's for X Prize's Mainstream Class. An Alternative Class can seat two or more and has no limit on number of wheels.)Cars must have an enclosed cabin (although convertibles are permitted), windshield wipers, seat belts, standard gauges, heater, air conditioning. They need to meet U.S. safety standards—meaning they can legally be sold for highway use in this country—as well as meeting standards in other nations.