The $10 million contest to produce a highly fuel-efficient car has moved to the validation stage, where the competitors will be tested on a dynamometer. The entries that exceed 100 mpg and meet performance and emissions requirements will win. Cash will be given out in September.

The event began in 2008 and had an original field of 136 vehicles from 111 teams all vying for a piece of the bounty. Now, just nine vehicles from seven teams remain. They just completed on-track testing at Michigan International Speedway and passed technical inspections.

The competition drew entrepreneurs, small companies and university squads from around the word.

“These finalists highlight true innovation in fuel efficiency, and prove that their vehicles have the ability to withstand strict safety, performance and emissions requirements,” said Eric Cahill, senior director of the X Prize. “These cars redefine what is possible and set a new standard of efficiency that promises to revolutionize the industry.”

Tata Motors could not present its Invica Vista EX vehicle for testing because of a technical issue. The company will demonstrate the vehicle’s abilities, though it won’t advance.

The event is organized by the X Prize Foundation and is sponsored by Progressive Insurance.
X Prize also did a space competition, and an entry backed by billionaire Paul Allen won in 2004. On Thursday, the foundation will announce another challenge--to clean up oil along the gulf coast.

The Finalists Are:
Mainstream Class (Two vehicles, one team)
-- Edison2, Very Light Car #97 (Charlottesville, Va.), Internal Comubstion Engine
-- Edison2, Very Light Car #98 (Charlottesville, Va.), Internal Combustion Engine
Alternative Class--Tandem (Two vehicles, one team)
-- X-Tracer, E-Tracer #72 (Switzerland), Battery Electric
-- X-Tracer, E-Tracer #79 (Switzerland), Battery Electric
Alternative Class--Side-by-Side (Five vehicles, five teams)
-- Aptera, Aptera 2e (San Diego, Calif.), Battery Electric
-- Li-ion Motors, Wave II (North Carolina), Battery Electric
-- RaceAbout Association, RaceAbout (Finland), Battery Electric
-- TW4XP, TW4XP (Germany), Battery Electric
-- ZAP, Alias (Santa Rosa, Calif.), Battery Electric