Car owners who always make safety a priority when shopping for a new vehicle don't always think about it when selecting a rental car at the airport.

Why the disconnect? It's often a matter of cost, and those on basic business trips sometimes aren't able to expense anything more than the economy option. Most rental vehicles, also, are newer; and there's an assumption (sometimes wrong) that newer is safer.

In fact, vehicles in rental fleets, according to the AAA, are less likely to get the latest safety-tech features than personal vehicles. Just a year or two ago, a wide range of vehicles—small cars especially—didn't come with standard electronic stability control (ESC), or even anti-lock brakes. And there are still a few base models in fleets that don't have ESC.

Crash-test ratings might be lower-than-typical for rental cars as well. According to an analysis from USA Today, more than 95 percent of 167 different models in rental fleets come with 'good' ratings from the IIHS in frontal crashes, which are the most common type in fatal accidents. In current rental fleets, USA Today found one 2010-model vehicle and six 2011-model vehicles with 'poor' side-impact ratings, though: the 2010 Chrysler PT Cruiser, the 2011 Chevrolet Colorado Crew Cab, the 2011 Kia Rio, the 2011 GMC Canyon, the 2011 Hyundai Accent, the 2011 Jeep Wrangler (2-door), and the 2011 Volkswagen New Beetle.

USA Today also found two 2011 models—the 2011 Cadillac STS, some 2011 Lexus HS 250h models, the 2010 Chrysler PR Cruiser, the 2010 Infiniti M35, and the 2010 Hummer H3—that are rated poor in the Institute's seat-based rear-impact tests.

Roof strength was particularly a weakness. Almost 40 percent of the rental vehicles that had been rated by the IIHS did not have 'good' ratings in the roof category, which measures occupant protection in the event of a rollover.

And if you think that you can reliably go by the model's safety ratings, according to the federal government or the IIHS, that's not completely true. In 2009, the Kansas City Star found that, to save money, Enterprise Rent-A-Car had deleted side airbags from 2006-2008 Chevrolet Impalas for its fleet. Because the Impala came with standard side airbags, renters (and some of those who bought the used rental cars from the fleet) could have wrongly assumed the vehicles were equipped with the important safety feature.

Though Enterprise broke the public trust, they did promptly offer to buy back those that had already been sold as used cars, and they haven't yet been found to have broken any law.

This year there's also been significant controversy over rental-car companies' responsibility to get recalled vehicles fixed—and whether they can keep them on the road if they are under a safety-related recall and haven't yet been fixed. According to a NHTSA study, Hertz Rent-a-Car fixed just 34 percent of its recalled vehicles within 90 days, while Avis and Budget fixed 53 percent and Enterprise fixed 65 percent within that period.

There have been exceptions, in a few cases of wider public unease. In the midst of the Toyota recall worries last year, Hertz, for instance, said that it would remove Toyotas from the fleet until repaired.

Yet, in browsing the sites of major rental companies, we didn't see safety features, or safety records, indicated in descriptions of vehicles. And in other cases, it was improperly or vaguely indicated with language like 'dual air bags.' Dual front airbags have been required on all new vehicles, by the way, for more than a decade.

Go here for some tips on how to choose a safe rental car, and let us know what you think. Are the rental cars missing out on a reason to get more people to upgrade? Would you be likely to change upgrade or change vehicles if the models' safety ratings were openly displayed?

[USA Today, LA Times]