With the market for hybrid automobiles picking up steam, it makes sense for tomorrow's engineers to get a feel for designing and building cars powered by a combination of internal combustion and electricity. Hybrid technology is far from an exact science, however, as student engineers found out last week at the Formula Hybrid International competition held at the New Hampshire Motor Speedway in Loudon, N.H.

Dartmouth College's fifth-annual Formula Hybrid competition called on student teams to conceive, design, fabricate, develop and drive formula-style hybrid-powered cars—weighing 180 kilograms to 270 kilograms—in a series of exercises testing their hot rods' acceleration, maneuverability and endurance. Before any car was allowed on the track, however, it needed to pass a technical inspection of its mechanical and electrical systems. Teams were also required to present a business case for their car as well as address their design objectives before a panel of judges.

These obstacles proved insurmountable for all but a handful of competitors. Of the 33 teams registered for the Formula Hybrid competition, only 21 showed for the tournament, a surprisingly thin field considering the event's past success. And when the rubber did meet the road, more than half of the teams failed their inspections, never even making it out of the pit area.

In the end Texas A&M University's team left competitors in its rearview mirror, followed by Brigham Young University, Lund University of Sweden, the University of California, Davis, and Dartmouth. Texas A&M was the only team on the track for all of the four main categories, which tested a car's electric-powered acceleration; general acceleration (fuel or electric); maneuverability and handling; and endurance—all over 22 kilometers (40 laps around the track). In 2010 14 of 24 teams competed in all four categories.

There were many reasons why this year's Formula Hybrid teams had difficulty passing inspection and making it to the track, but foremost was the ambitious approach that most took when designing their cars, says Dartmouth engineering innovation professor John Collier, also the Dartmouth team's faculty advisor. "I think the kids were reaching further by trying to have more complex technology, and that was much harder to make work," he adds.

Dartmouth's team, for example, could have based their car on "a perfectly good carbureted Honda engine," Collier says. Instead, the students this year opted for a fuel-injected system to improve gas mileage. The fuel-injected Honda engine, however, did not come with an electric motor starter, which made switching from gas to electric power more complicated. "So the students added an enormous amount of complexity just to get their car to run the way they designed it," he adds. The students worked until the eleventh hour preparing their car for the competition—the Dartmouth entry had never even made a test run under its own power prior to the final day of the competition.

Many teams eschewed straightforward approaches to marrying fuel and electric power. Instead, some designed cars with an electric motor for each wheel. "So all of a sudden you're trying to control four motors, and you know that if you don't control them separately it's going to be a very difficult thing to steer," Collier says. With four motors, "you also need a computer that senses what's going on at each wheel, which means you have to put a speed sensor in each wheel."

Students faced another challenge developing hybrids: The technology is still relatively new, so there are not a lot of standard components that fit a variety of designs. "There aren't any parts that you could take out of an existing hybrid and use in another hybrid," Collier says. "None of the parts are off-the-shelf connections."

It was a strange year, Collier admits, adding, "I think next year you'll see teams getting their cars ready earlier."

View a slide show of this year's competition