Subcompact cars performed the worst of any vehicle segment so far in a tough new crash test.
The so-called small overlap front crash test assesses what happens when the front corner of a vehicle hits another car, a utility pole or tree, but only one of 11 minicars tested by the Insurance Institute for Highway Safety (IIHS) won an overall "acceptable" rating – the Chevrolet Spark made by General Motors.
The Honda Fit and Fiat 500, made by No. 3 US automaker Chrysler Group LLC, were the worst performers and the results prompted Consumer Reports magazine to drop its recommendation of the Fit on Wednesday.
Four minicar models were rated "marginal", including the 2014 Ford Fiesta. Six were rated "poor", including the Toyota Prius c. None of the models received the best possible rating of "good".
Both Consumer Reports and IIHS said small, lightweight cars are at a safety disadvantage because of their size. In a crash with a larger vehicle, a minicar will absorb more energy but have less crumple space to absorb the energy of a collision.
"Small, lightweight vehicles have an inherent safety disadvantage," Joe Nolan, IIHS senior vice president for vehicle research, said in a statement. "Unfortunately, as a group, minicars aren't performing as well as other vehicle categories in the small overlap crash."
The small overlap front crash test, which was introduced in 2012, is tougher than head-on crash tests used by the US government, according to automakers and IIHS, a US non-profit funded by auto insurers.
In the test, part of the car's front end hit a 5ft rigid barrier at 40mph. The vehicles were rated in three areas: structural integrity, the effectiveness of the restraints and potential injuries.
All the minicars, including the Spark, got a "poor" or "marginal" rating for structural integrity, which IIHS called "the most fundamental element of occupant protection". These are the two worst ratings possible in this test.
Most cars are now built with safety cages that can handle head-on collisions and other crashes without crushing the driver and others inside the vehicle.
Small overlap crashes, involving only the small front corner of a vehicle, affect the outer edges of the car, which are less protected. In those cases, the front wheel, suspension system and firewall bear the brunt of the crash, which can lead to serious leg and foot injuries.
Consumer Reports said, however, that it expected the upcoming, newly redesigned 2015 Fit to pass the test "based on the newness of its design and Honda's recent accomplishments with this stringent test".
In a statement, Honda said it expects the 2015 Fit will earn a "good rating" on all IIHS tests, including the small overlap front crash test. The 2015 Fit goes on sale in the USA later this year.
Separately, Chrysler said the Fiat 500 "meets or exceeds all government-mandated safety requirements and continues to offer a high level of protection in four main crash types identified by the IIHS: side, rollover, rear and moderate-overlap front."
Compact cars, which are slightly larger than subcompacts, fared "much better" on the small overlap front crash test, IIHS said. The average vehicle made for the 2013 model year weighs 4,041lb (1,821kg), while subcompacts can weigh 1,500lb (680kg) less, according to preliminary federal data.