Given modern engineering, design and manufacturing, most drivers probably assume that new cars are inherently safe. But, according to a study by the nonprofit group Insurance Institute for Highway Safety, that isn't necessarily the case.

In fact, the group recently reviewed a range of new models and found seven that were lacking in safety.

The IIHS rated cars based on a frontal offset crash test, a side-impact crash test, resistance to rollovers, and rear-impact protection and found that seven models performed either "marginally" or "poor."

The worst performer was the Dodge Ram 1500, which received a "marginal" grade in both side-impact and rollover tests. Despite the fact that the truck has a history of poor safety, the model has sold well, with Dodge moving more than 100,000 trucks each year from 2007 to 2011.

The Chevy Colorado, which is essentially the same truck as the GMC Canyon, was next, with a "poor" rating for side-impact and "marginal" grades for both rollover and rear crash safety. Sales of the Colorado have been lackluster recently, with Chevy selling 75,716 cars in 2007 and only 31,026 in 2011. In November of 2011, a recall of Colorados and Canyons due to seat belt concerns further tarnished the truck's safety record.

The $22,190 Mazda CX-7 came in third. Although it received decent marks for front and side-impact tests, the model scored a "marginal" for rollover and rear-impact. Despite that, sales for the car rose by about 20,000 units to 35,641 in 2011. This is still short of sales figures in 2007, however, when 42,199 CX-7s were sold.

The Maxda CX-9, Nissan Pathfinder, Jeep Wrangler and Suzuki SX4 rounded out the list. Despite their poor performance in safety tests, several of these models are selling well in the U.S., according to Edmunds sales data. The Wrangler, for example, received the lowest score of any mid-size SUV from Consumer Reports, but sold a whopping 120,000 units in 2011.

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