The pool of contestants battling for the Progressive Automotive X Prize has been slashed in half.

The organiser of the $10million contest to develop next-generation green cars or vehicles has trimmed the number of contestants to 43 teams from 10 countries which have passed the vehicle design phase. The teams range from Indian car giant Tata Motors to a team of Cornell University engineering students, and they will now move to a performance and safety testing phase.

According to Peter Diamandis, the X Prize CEO and chairman, the teams and vehicles represented in this group are the most viable in the competition and could potentially have a huge impact on the automotive marketplace.

The prize is awarded to teams that develop viable, production-capable vehicles that exceed 100mpg. The remaining teams are submitting a range of vehicles powered by different fuel types with Tata focusing on a battery powered electric vehicle and the Cornell students looking at a hybrid diesel-electric race car. Other teams have presented vehicles powered by biofuels, petrol and other fuels.

As for the prize money, that will be split into two categories: mainstream cars, which must carry four or more passengers and have four wheels; and alternative vehicles that have less stringent requirements. Of the remaining teams, 28 are classed as ‘mainstream’ and 25 are classed as ‘alternative’.