The Insurance Institute for Highway Safety (IIHS) announced that the number of vehicles earning either of its two awards has jumped to 71 from 39 this time last year. The number of winners in the top tier – Top Safety Pick+ – has increased by 11 for 2015, despite a tougher standard for front crash prevention.

“This is the third year in a row that we are giving automakers a tougher challenge to meet,” says IIHS President Adrian Lund. “The quest for Top Safety Pick and Top Safety Pick+ awards is driving improvement in the small overlap front crash test and getting manufacturers to offer automatic braking technology on more and more vehicles.”

While the bar has been raised for Top Safety Pick+, the criteria for Top Safety Pick are unchanged: a good or acceptable rating in the small overlap front test and a good rating in each of the Institute’s four other crashworthiness evaluations – moderate overlap front, side, roof strength and head restraints. The 2015 Top Safety Pick+ designation is awarded to vehicles that meet those criteria and also have an available front crash prevention system that earns an advanced or superior rating.

For 2014, vehicles could qualify for Top Safety Pick+ with only a basic rating for front crash prevention. Warning systems that meet the National Highway Traffic Safety Administration’s performance criteria but don’t include autobrake qualify for a basic rating. For an advanced or superior rating, vehicles must stop or slow down without driver intervention before hitting a target in IIHS tests at 12 mph, 25 mph or both.

As a result of the change in criteria for 2015, 15 vehicles that qualified for 2014 Top Safety Pick+ are now simply Top Safety Pick winners. In all, there are 33 Top Safety Pick+ winners and 38 Top Safety Pick winners.

“Although forward collision warning on its own is a valuable feature, we decided to tighten our criteria to encourage manufacturers to offer autobrake. Systems that don’t require a driver response to avoid or mitigate a crash have the most potential for reducing crashes,” Lund says. “Nevertheless, the models that are losing their plus signs are still great choices for safety, as are all the Top Safety Pick winners.”

Meeting the Small Overlap Challenge

Most vehicles produced in recent years have had little trouble with the Institute’s moderate overlap front, side, roof strength and head restraint tests. The small overlap front test, which replicates what happens when the front corner of a vehicle collides with another vehicle or an object such as a tree or utility pole, represented a new hurdle when it was introduced in 2012. The test is difficult because the crash forces bypass most of a vehicle’s energy-absorbing structure. But small overlap crashes are common in the real world, so the Institute wanted to push manufacturers to look for solutions.

For 2013, IIHS continued to award Top Safety Pick to vehicles that earned good ratings in the four older tests, regardless of their small overlap ratings. Those with good or acceptable small overlap ratings earned Top Safety Pick+. Only 13 vehicles managed it at the beginning of the award year.

Since then, automakers have steadily increased the number of good or acceptable small overlap ratings by factoring in the test when they redesign a vehicle or introduce a new model and by making modifications to the structure and airbags between redesigns.

The Honda CR-V, a 2015 Top Safety Pick+ winner, is an example of a vehicle that was successfully modified for improved protection. Previously, the small SUV earned a marginal rating when it was tested in 2012. The structure didn’t hold up, with intrusion into the driver space exceeding one foot. The dummy’s head barely contacted the front airbag before sliding off as the steering column moved to the right.

Honda made changes to the vehicle’s front-end structure, occupant compartment and restraint system for the 2015 model year. In the most recent test, maximum intrusion was five inches at the parking brake pedal, and the dummy’s head remained on the front airbag until rebound. Today’s CR-V earns a good rating.

The Toyota Prius v, which also earns Top Safety Pick+, saw even greater improvement. The midsize car had been one of the worst performers ever in the small overlap test. In 2012, the structure collapsed, and the dummy’s head hit the instrument panel and ended up between the side curtain airbag and the door. Measures from the dummy showed left hip and lower leg injuries were very likely.

After the structure was improved and the side curtain airbag was lengthened, the 2015 Prius v performed well all-around, with low levels of intrusion, good restraint performance and low injury measures.

Manufacturers are employing some common strategies when it comes to beefing up structure for small overlap protection. In the CR-V’s case, the door frame was strengthened, and the side frame under the fender was reinforced. The beefed-up side frame ties into the main frame rail, producing an additional load path for energy absorption. On the Prius v, the front bumper was extended and the door frame strengthened. In addition, structure was added to better tie the door-hinge pillar to the frame rail.

Front crash prevention spreads

The list of 2015 Top Safety Pick+ winners shows how quickly front crash prevention systems with autobrake are spreading. In total, there are 27 superior-rated 2015 models and 33 with an advanced rating. (Some of those vehicles don’t qualify for Top Safety Pick+ because they don’t meet all the crashworthiness criteria.)

Most of the Top Safety Pick+ winners earn the award only when equipped with optional front crash prevention systems. However, when not equipped, they still meet the crashworthiness criteria for Top Safety Pick.

Currently only three automakers offer standard front crash prevention systems. Volvo models have standard City Safety, a low-speed autobrake system. The Mercedes-Benz C-Class and E-Class have a warning and autobrake system, but the standard autobrake components haven’t been tested yet. The Mercedes-Benz M-Class and CLA and the Acura RLX offer standard warning systems. All these vehicles are available with optional systems that earn higher ratings than the standard equipment. The CLA, which earns an advanced rating with its optional system, hasn’t been tested for crashworthiness.