When it comes to buying a new convertible, a hefty price tag doesn't always buy safety. Test scores being released Thursday by the Insurance Institute for Highway Safety found several affordable convertibles offer better crash protection than more expensive competitors.

Conducting tests on 10 new midsize convertibles for the first time, the institute gave its top scores to two expensive convertibles — the 2007 Saab 9-3 and 2007 Volvo C70. Both vehicles, which start at nearly $40,000 US, received the highest scores on front, side-impact and rear crash protection tests.

"The performances of the 9-3 and C70 are impressive," said Adrian Lund, the institute's president. "These cars combine what convertible buyers should look for if they're shopping with safety in mind."

Convertibles, a luxurious second car for many owners, are a small part of the new car market, comprising about two per cent of vehicle sales, according to J.D. Power and Associates.

Less expensive convertibles get high marks

While many owners can afford to use their roadsters on weekends during the summer, the tests suggest that safety doesn't have to be a simple function of cost. Three convertibles — the 2007 Mitsubishi Eclipse Spyder, 2007 Volkswagen Eos and 2008 Chrysler Sebring — received the highest marks in front- and side-impact crash testing. All start under $30,000 US.

The 2007 BMW 3 Series and the 2007 Audi A4 Cabriolet, meanwhile, received the institute's second-lowest score in side-impact tests. The BMW convertible starts at $43,200 US, while the A4 model starts at $39,100 US. Both received the highest ratings in frontal tests.

During its side test of the 3 Series, for example, the institute recorded injury measures on the driver dummy that could indicate rib fractures and injuries to internal organs in a similar crash.

BMW AG spokesman Thomas Plucinsky said the automaker was disappointed with the side-impact results but said it engineers its vehicles to pass a wide range of crash tests around the world.

"We're confident that in real-world situations that BMW vehicles are among the safest in side impact," he said.

Audi AG spokesman Patrick Hespen said the A4's vehicle platform debuted in late 2002, before the institute's testing procedures were implemented. He said the vehicle "provides a high level of crash protection."

Roll bars prevent rollovers

Among other vehicles tested, the 2007 Toyota Camry Solara received the highest rating in the frontal test and the second-highest mark in side evaluation.

The Ford Mustang, meanwhile, received the second-highest ranking in front-end testing and the highest marks in side impact.

Lund said consumers should look for roll bars, which help reduce the risk if the convertible rolls over.

Pop-up roll bars, which deploy automatically if the sensors detect a potential rollover, are standard equipment on the 9-3, C70, Eos, 3 Series and A4, but unavailable on the other vehicles tested.