We've all heard the argument for why someone drives that big SUV instead of a fuel-sipping mini-car on their epic two-hour commute: crash safety. And while there's a good bit of sense to that point, at least from the SUV driver's perspective, small cars are improving their safety marks according to the latest round of Insurance Institute for Highway Safety (IIHS) testing.

Only one of the cars tested scored poorly, and though none did well enough to secure the IIHS 'Top Safety Pick' award, most did surprisingly well. The testing involves frontal and side impacts plus whiplash testing on the front seats. The side-impact sled, weighted at 3,300lb (1,500kg), simulates a somewhat larger car striking the small cars, which in the case of the Mini Cooper, at least, weigh as little as 2,500lb (1,130kg).

The best performers were the Suzuki SX-4 and the Pontiac Vibe/Toyota Matrix. Both scored Good/Good in front impact and side impact ratings. The SX-4 scored 'marginal' on seat whiplash protection, while the Vibe/Matrix wasn't tested. The only small car to perform poorly in the testing was the aging Chrysler PT Cruiser, which score Poor in side impact and Poor in whiplash protection, though it did earn a Good rating in frontal impact testing.

The Poor rating means passengers in the PT Cruiser were likely to suffer serious injuries in the event of a side impact. Part of the score is the result of the unavailability of side airbags for rear-seat passengers.

Other top scorers include the Ford Focus sedan, which earned Good and Acceptable marks in front and side impact protection, while also earning a rating of Good in whiplash protection. Chevy's HHR scored similarly to the Focus, but with only Marginal protection from whiplash. It does, however, feature standard electronic stability control on all 2009 models.

"Automakers have made big improvements to small cars to better protect people in frontal crashes," said Joe Nolan, an Institute senior vice president. "They've also added stronger structures and standard head-protecting side air bags to help in side crashes, which are tougher on smaller, lighter cars."

Improvements in side impact protection have also been dramatic in a short period of time. Two years ago, only three of 19 cars tested received a top rating of Good in side-impact testing, while this time around 11 of the 21 cars tested achieved the top mark.