In test results released April 14, the Insurance Institute for Highway Safety found that drivers of 2009 versions of the Smart Fortwo, Honda Fit and Toyota Yaris could face significant leg and head injuries in severe front-end crashes with larger, midsize vehicles.

In the Fortwo collision, the institute said the Smart, which weighs 1,808 pounds, went airborne and turned around 450 degrees after colliding with a 2009 Mercedes C Class, which weighs nearly twice as much. There was extensive damage to the Fortwo's interior, and the Smart driver could have faced extensive injuries to the head and legs. There was little damage to the front seat area of the C Class.

Smart USA President Dave Schembri said the test simulated a "rare and extreme scenario." The Fortwo has received top scores from the Insurance Institute in front-end and side crash tests against comparably sized vehicles, but it got poor marks against the larger C-Class.

In the Honda Fit's 40-mph head-on crash against the 2009 Honda Accord (click the play button above to launch video), the Fit dummy's head struck the steering wheel through the air bag and showed a high risk of leg injuries. In the vehicle-to-vehicle test, the Fit was rated poor while the Accord's structure held up well.

Honda spokesman Todd Mittleman said the tests involved "unusual and extreme conditions" and noted that all 2009 Honda vehicles had received top scores from the Insurance Institute.

"There are good reasons people buy minicars. They're more affordable, and they use less gas. But the safety trade-offs are clear from our new tests," said Adrian Lund, the institute's president.

The institute has raised questions about whether stricter gas mileage rules, which are being developed by the government, might lead to smaller, lighter vehicles that could be less safe. Continued: Crash test: Toyota Yaris vs. Camry

In the Yaris test (click the play button above to launch video), the institute said the minicar sustained damage to the door and front passenger area when it crashed head-on into a 2009 Toyota Camry. The Yaris driver dummy showed signs of head injuries, a deep gash on the right knee and extensive forces to the neck and right leg.

The Yaris has received good ratings in past front and side testing but received a poor rating in the crash with the Camry. Toyota spokesman John Hanson said the car-to-car test had little relevance to consumers because of its severity.

"It's fairly obvious that they have an agenda here with regard to how smaller cars are going to be entering the North American market in larger numbers," Hanson said.

Sales of small cars soared when gas prices topped $4 per gallon last year but have fallen off as gasoline has retreated to about $2 a gallon and the economic downturn has slowed car sales. Continued: What do you think?

Tell us if the crash tests had an impact on your opinion. Take the MSN Money's poll (above), then tell us your thoughts about the results on the Consumer Action message board: Are minicars' economic value worth their safety risk?