(from the Detroit News) Washington— Only one small car out of 12 — BMW’s Mini Cooper Countryman — earned a “good” rating earning from the Insurance Institute for Highway Safety in its latest round of tough, new front-end crash testing.

The latest testing marked the first time electric cars have been subjected to the challenging IIHS small-overlap front crash test: General Motors Co.’s plug-in hybrid Chevrolet Volt earned an “acceptable” rating, while the EV Nissan Leaf was rated “poor.”

The Volt was the only car to receive a Top Safety Pick+ award, because it is the only one with an available front crash prevention system. The other five cars that got “good” or “acceptable” ratings were given Top Safety Pick awards. They include the Mini Cooper and the four other cars with “acceptable” ratings: Ford C-Max Hybrid, Mitsubishi Lancer, Scion FR-S and Subaru BRZ.

“Vehicle and customer safety is of utmost concern to us,” said Jeff Boyer, vice president of GM Global Vehicle Safety. “GM is committed to outstanding results from all of the safety tests we are a part of — the recognition of the Chevrolet Volt as a Top Safety Pick+ vehicle is a testament to that.”

Many consumers consult IIHS ratings when buying a car, and automakers tout the awards in advertising.

Two cars in the latest testing were rated “marginal” for occupant protection: Hyundai Veloster and Scion xB. Four were rated “poor”: Fiat 500L, Nissan Juke, Nissan Leaf and Mazda5.

Introduced in 2012, the small-overlap front crash test replicates what happens when the front corner of a vehicle hits another vehicle or an object like a tree or utility pole. In the test, 25 percent of a vehicle’s front end on the driver’s side strikes a rigid barrier at 40 mph.

The test is more difficult than the head-on crashes conducted by the National Highway Traffic Safety Administration. It poses a challenge for the vehicle to manage crash energy.

“Collapse of the occupant compartment is the downfall for four small cars in this group, including the Fiat 500L, Mazda5, Nissan Juke and Nissan Leaf,” said Joe Nolan, senior vice president for vehicle research for the IIHS. “A sturdy occupant compartment allows the restraint systems to do their job, absorbing energy and controlling occupant motion.”

The Arlington, Va.-based insurance industry-funded group prods automakers to build safer cars. It has now rated 32 small cars for protection in small-overlap front crashes. Of them, 19 earn a good or acceptable rating and 13 earn marginal or poor.

In 2011, the Volt and Leaf were the first plug-in electric models to undergo IIHS crash test evaluations — and both earned top ratings in the moderate overlap front, side, head restraint and roof-strength evaluations.

But both faced challenges with the newest test.

“Electric vehicles have a unique challenge in the small overlap test because of their heavy batteries. The Volt performed reasonably well, earning an acceptable rating, while the Leaf struggled,” Nolan said.

Driver space in the Volt was “maintained reasonably well in the test, and injury measures taken from the dummy indicate a low risk of any significant injuries to a person in a similar crash,” IIHS said.

In the Leaf, the dummy had significant damage. The instrument panel, parking brake pedal and steering column were pushed toward the driver. Injuries to the left knee and left lower leg would be likely in a crash of this severity, and injuries to the left thigh would be possible.

Nissan said in a statement it will review results “as we seek opportunities for improvement.”

The Countryman, introduced in 2011, is a larger four-door version of the two-door Mini Cooper. The small overlap rating for the Countryman doesn’t apply to the two-door model, which hasn’t been tested.

To earn the top rating of “good,” automakers need to focus on overall crash protection. That means an occupant compartment that resists intrusion, safety belts that prevent a driver from pitching too far forward and side-curtain air bags that provide enough forward coverage to cushion a head at risk of hitting the dashboard, window frame or things outside the car.

In the Fiat 500L, a four-door variant of the Fiat 500 coupe, intruding structure seriously compromised the driver’s survival space, knocking the steering wheel back and to the right of the driver. As a result, the front air bag was out of position so the dummy’s head slid off the left side and hit the A-pillar. IIHS said serious injury to the driver’s left hip would be likely, and injuries to both lower legs would be possible in a real-world crash of this severity.

Chrysler said in a statement that “the Fiat 500L continues to offer a high level of protection in the four main crash types identified by the IIHS — side, rollover, rear and moderate-overlap front. No single test determines overall safety.”

The Mazda5 was the lowest-rated vehicle in the test. “When we tested the Mazda5 we saw a host of structural and restraint system problems. Parts of the occupant compartment essentially buckled, allowing way too much intrusion,” Nolan said.

In a statement, Mazda said, “We take these results seriously, and are studying the results of these IIHS tests as we consider the design of future vehicles.”