SAN FRANCISCO -- Weight is the third fuel.

Although many companies are promoting batteries and biofuels as a way to wean the world off of fossil fuels, mass and aerodynamics play a significant, if often unrecognized role, in increasing mileage, according to Mike Brylawski, the vice president of corporate strategy at Bright Automotive. We interviewed him during Reinventing Fire, a conference being held by the Rocky Mountain Institute in San Francisco.

Bright is designing a lightweight, hybrid delivery van slated to come out in 2013. It will drive 40 miles on electric power and then 40-miles on a combination of gas and electric power, similar to how a Prius drives. Bright spun out of RMI earlier this year. Vans only get around 10 to 16 miles per gallon, so increasing mileage in these kinds of cars can translate into massive cuts in liquid fuel consumption. 900,000 new delivery vehicles get sold a year in Canada, the U.S. and Mexico, he added.

Swapping out steel in the body chassis provides the biggest gains in weight loss. Bright wants to employ aluminum and is also working to integrate composites in other elements. Although the Tesla Roadster has a carbon fiber chassis, carbon likely won't be cheap enough for mainstream cars for five to ten years, if then. The second biggest way to lose weight is "platform physics," i.e., fit and finish and studying everything in the car for weight reduction.

Bright's vehicle will also be more aerodynamic than normal U.S. delivery vans. Besides making cars, it is consulting with car companies.

The company is based in Indiana, which he calls the Silicon Valley of Electric cars. Several component and battery companies are within a short drive.