Audi revised the A6 front structure to ace the small-overlap test, but only cars built after January carry the modified design.

The 2016 Audi A6 has received a Top Safety Pick+ rating from the Insurance Institute for Highway Safety, but prudent buyers must check the assembly date.The midsize luxury sedan already had 'good' ratings for the side, roof strength and moderate-overlap front crash tests, however the IIHS waited until Audi revised the front structure before putting the car through the more challenging small-overlap trial.

The revised A6 has not received a 'good' rating in the small-overlap scenario, with a maximum intrusion of four inches and well-controlled movement of the test dummy. Measurements taken from the dummy suggest there is low risk of significant injuries in a similar real-world crash.

"The good small overlap rating applies to A6s built after January," the IIHS report notes.

The organization achieved mixed results when testing the A6's optional front-crash prevention system. The braking intervention reduced the vehicle's speed by 10 mph in the lower-speed test, but only by 1 mph in the high-speed test.

Other Top Safety Pick Plus cars in IIHS' large luxury category include the Hyundai Genesis, Mercedes-Benz E-Class, Infiniti Q70, Volvo S80, Lexus RC and Acura RLX. The BMW 5-Series and Lincoln MKS fell short, earning marginal or poor ratings in the small-overlap test.