The 2015 Volkswagen Jetta has captured the Insurance Institute for Highway Safety's highest award, Top Safety Pick+, thanks to a structural upgrade that improves small overlap protection and the addition of an optional front crash prevention system.

The car didn't get a full redesign, but Volkswagen strengthened the A-pillars and doorsills for the 2015 model year. As a result, the Jetta's small overlap rating improved to “good,” compared with the “marginal” rating of earlier models.

In the test, the driver's space was maintained well, and measures taken from the dummy in the driver seat indicated a low risk of any significant injuries in a crash of the same severity, IIHS said.

“The side airbag deployed and had sufficient forward coverage to protect the head from striking side structure and outside objects,” IIHS said in a press release. “However, the dummy's head slid off the frontal airbag after hitting it, and the safety belt allowed the dummy's head and torso to move too far forward.”

In addition to the “good” small overlap rating, the Jetta drew “good” ratings in the institute's four other crashworthiness evaluations. An optional forward collision warning system drew the car a “basic” rating for front crash prevention. When equipped with the system, the Jetta qualifies for the Top Safety Pick+ award.

IIHS introduced the small overlap evaluation in 2012. In the test, 25 percent of a vehicle's front end on the driver side strikes a rigid barrier at 40 mph. The crash replicates what happens when the front corner of a vehicle collides with another vehicle or an object such as a tree or a utility pole.

To qualify for Top Safety Pick, a vehicle must draw a “good” or “acceptable” rating for small overlap protection and “good” ratings in the IIHS moderate overlap front, side, roof strength and head restraint tests. Top Safety Pick+ winners must meet those same criteria and also earn a “basic,” “advanced” or “superior” rating for front crash prevention.