In a two-vehicle accident involving a Hummer and a Chevy Aveo, common sense seems to indicate you would be safer in the larger, heavier Hummer. But that doesn’t have to be the case, according to a new study.

A vehicle’s safety is dependent on its engineering - not it’s girth, said Laura Schewel, an analyst at the Rocky Mountain Institute in Snowmass, Colo.

Schewel’s reseach indicates a small, lightweight vehicle should perform just as well or better than a heavier one if it is designed differently.

Schewel presented her study last week in Detroit at the Society of Auto Engineers’ World Congress. In her work for the Rocky Mountain Institute, Schewel studies ways vehicles can be more environmentally friendly.

While environmental groups have long suggested decreasing a vehicle’s weight in order to reduce fuel consumption, others worry it would also compromise passenger safety.

Schewel said that is a misconception. Primarily, safety rests in the drivers hands. But she said a vehicle’s dimensions have more to do with safety than weight. “When you get into a car that’s big and light, that’s the ultimate safety,” Schewel said. “A car that is long and wide gives crush space and more materials to absorb energy in the right way.”

Shewel said injuries and fatalities occur when people come into contact with something - their own car, other objects involved in the accident or if they are thrown from the car. But if a car is spacious enough that no part of it comes into contact with its occupants during a crash, “ultimate safety” is achieved.

Of course, she calls that that height of safety because it would enhance safety for the environment as well.

“People have a very intuitive reaction to protect themselves,” she said. “It’s also right to be afraid of global warming. You should put those fears together and design to allay them simultaneously.”

Her finding impressed at least one group. The paper attracted a $200,000 grant from The William and Flora Hewlett Foundation. The Rocky Mountain Institute will use the cash to conduct virtual crash tests on vehicles that weigh about half the average weight of today’s vehicles.