Side curtain airbags are standard on Chevrolet Impalas and Cobalts, but when Enterprise Rent-A-Car ordered 66,000 of those models for its fleet the air bags were not installed as a cost-saving measure, according to the group Safety Research & Strategies. Enterprise then compounded the safety hazard by reselling some of the 2006, 2007, and 2008 Impalas and the 2008 and 2009 Cobalts to unsuspecting used-car buyers. Ads for some of the cars on the Enterprise Web site mistakenly claimed they had side curtain air bags.

“I’ve never seen a standard safety feature removed from a vehicle,” said SRS's Sean Kane in a report on his group's work in the Kansas City Star. “That’s what’s so unique about this. I’ve been doing this work for 17 years and, until now, had yet to see this happen.” 

Enterprise Rent-A-Car, according to the Star, is the nation’s largest private buyer of new cars and seller of used ones. The company saved $175 per car by not having the side curtain air bags installed, a total of $11.5 million.

“We were quite frankly surprised by the whole situation,” said Tony Di Viesta, another safety expert at SRS. “If you had gone to a GM dealership and bought one of these cars you would have gotten the side curtain airbags as a standard feature. It’s really troubling they were selling them as fleet vehicles without the side curtain air bags.”

Enterprise officials defended their decision to delete the side air bags as one that did not violate any federal mandate, according to The Star. But the St. Louis-based company admitted making a mistake in its online advertising and is sending letters to 745 consumers who bought the mislabeled used cars.

Side impact crashes are the second most frequent type and often result in serious head injuries—the most common type of injury regardless of crash angle. In 2007, nearly 4,000 vehicles were involved in a fatal side-impact crash, according to Safety Research & Strategies.

Consumer Reports thinks side curtain air bags are an extremely important safety feature, particularly in sedans such as the Impala and Cobalt.

“Tests show that head-protecting side air bags are especially important in sedans, which are vulnerable in side crashes with SUVs or pickups,” our auto editors wrote in CR's Dream Car. “We think that side air bags, which primarily protect the torso, and side-curtain air bags, which protect the head, should be standard in all vehicles.”

The full investigation by Safety Research & Strategies is featured on its Web site.

To see how the Chevy Impala—or your own car—performs in crash tests, visit our crash test video hub.