The U.S. government’s new vehicle crashworthiness ratings may have claimed two victims already, the high-profile Toyota Camry compact sedan and the Nissan Versa subcompact. They are the only two vehicle models of the 55 tested so far to score fewer than four stars in the system’s combined rating.

The 2011 Camry, one of the nation’s top-selling family sedans, will carry a combined three-star rating, the Nissan a two-star rating. Most of the others tested by the National Highway Traffic Safety Administration will carry four stars, and only two, a BMW 5-Series and a Hyundai Sonata, will be awarded five stars, the top safety rating.

Though neither Toyota nor Nissan criticized the new rating system, the Camry and Versa could suffer in the marketplace if shoppers decide that competitive 2011 models with more stars are safer and, therefore, a better choice for purchase. Some consumers, noticing that ratings on many 2011s have gone down -- or vanished altogether -- may presume, incorrectly, that they’re less safe than their predecessors.

“Consumers already think cars are safe,” said Wade Newton, a spokesman for the Alliance of Automobile Manufacturers, a trade organization representing 12 manufacturers that sell in the U.S. “The government has raised the bar by making new tests and more complex tests. It’s sort of like when the teacher saw that everyone was getting an A, it was time to make the tests harder.”

Or, as one manufacturer’s spokesman said anonymously in order to avoid offending NHTSA: “Four stars is the new five.” He added that manufacturers are sure to take steps soon to make sure that their vehicles can pass the newly stringent crash tests.

The new rating system comes at a time when the rate of vehicle fatalities in the U.S., as tallied by the federal government, has fallen to an all-time low. One reason for the lower death toll is that cars have never been equipped with as many mandated safety features, such as airbags and stability control. Higher-end models come equipped more and more with sophisticated accident-avoidance technology, such as blind-spot warnings and adaptive cruise control that can reduce a vehicle’s speed before it rear-ends a slower-moving vehicle ahead.

The 2010 Camry, virtually the same vehicle as the 2011, was awarded five stars for frontal and side impact crashworthiness and four stars for its performance in the rollover test. Versa, also unchanged from its 2010 counterpart, notched two stars in the combined score for 2011. Under the previous system Versa scored four stars in each of the three main categories.

The government plans to continue evaluating vehicles under the new testing regime, but until that happens models that haven’t been tested will carry no safety rating.

Brian Lyons, a spokesman for Toyota, said the company doesn’t have specific results yet from the tests, so it doesn’t know the reason for the ratings. Citing information from a NHTSA website, Lyons said in an e-mail response “one of the new tests uses different sized dummies that collects more data [which] is where the difference is in the front and side impact results when compared to last year.”

NHTSA said that it was using a new type of crash-test dummy that is smaller and more accurately measures the effects of a crash on a woman’s body. The government also described a new “pole test” that assesses damage when a vehicle collides with a tree or a telephone pole.

Scott Vazin, a Nissan spokesman, said “because testing guidelines are stricter, 2011 model ratings are not comparable to 1990-2010 vehicles. The Nissan Versa has performed well in real world crashes and provides our customers with good real-world safety protection. Nonetheless, we will study NHTSA's test results and take the appropriate action to ensure we deliver a high-level of real-world safety.“

Top Safety Picks 2010 from the Insurance Institute for Highway Safety
LARGE CARS
Buick LaCrosse
Ford Taurus
Hyundai Genesis (built after 1/2010)
Lincoln MKS
Mercedes E class (built after 1/2010)
Volvo S80

SMALL CARS
Honda Civic (4-door (except Si) with optional ESC)
Kia Forte (built after 10/2009)
Kia Soul
Nissan Cube
Scion xB
Subaru Impreza (except WRX)
Toyota Corolla
VW Golf (4-door)

MIDSIZE CARS
Audi A3
Chevrolet Malibu (built after 11/2009)
Chrysler Sebring (4-door w/optional ESC)
Dodge Avenger (with optional ESC)
Hyundai Sonata (2011 models)
Mercedes C class
Subaru Legacy
Subaru Outback
Volkswagen Jetta (sedan)
Volkswagen Passat (sedan)
Volvo C30 (2010-11 models)
MIDSIZE SUVs
Dodge Journey
Subaru Tribeca
Volvo XC60
Volvo XC90

SMALL SUVs
Honda Element
Jeep Patriot (w/optional side torso airbags)
Subaru Forester
Volkswagen Tiguan