In this April 2017 photo provided by the Insurance Institute for Highway Safety, during a 35 mph crash test, a steel and fiberglass underride guard prevents a car from going underneath a tractor-trailer. Federal law requires big trucks to have rear underride guards, which stop cars from traveling underneath the truck in an accident. But the government doesn’t require side guards. The Insurance Institute for Highway Safety says side guards could prevent hundreds of traffic deaths per year. (Insurance Institute for Highway Safety via AP)
In this April 2017 photo provided by the Insurance Institute for Highway Safety, a Chevrolet Malibu underrides a tractor-trailer in a 35 mph crash test. The trailer has an aerodynamic skirt but no underride guard. Federal law requires big trucks to have rear underride guards, which stop cars from traveling underneath the truck in an accident. But the government doesn’t require side guards. The Insurance Institute for Highway Safety says side guards could prevent hundreds of traffic deaths per year. (Insurance Institute for Highway Safety via AP)
This Sept. 15, 2016, photo provided by the Insurance Institute for Highway Safety shows a Tesla Model S during crash safety testing. The car earned good ratings in four of the institute’s five tests, but fell short of getting the highest safety rating in the newest crash tests administered by the insurance industry. (Matt Daly/Insurance Institute for Highway Safety via AP)
This Sept. 7, 2016, photo provided by the Insurance Institute for Highway Safety shows a Tesla Model S before crash safety testing. The car earned good ratings in four of the institute’s five tests, but fell short of getting the highest safety rating in the newest crash tests administered by the insurance industry. (Matt Daly/Insurance Institute for Highway Safety via AP)
This Oct. 4, 2016, photo provided by the Insurance Institute for Highway Safety shows a 2017 BMW i3 during crash safety testing. The car earned good ratings in four out of five tests, but fell short of getting the highest safety rating in the newest crash tests administered by the insurance industry. (Matt Daly/Insurance Institute for Highway Safety via AP)
This Sept. 20, 2016, photo provided by the Insurance Institute for Highway Safety shows a 2017 BMW i3 before crash safety testing. The car earned good ratings in four out of five tests, but fell short of getting the highest safety rating in the newest crash tests administered by the insurance industry. (Matt Daly/Insurance Institute for Highway Safety via AP)
This undated photo provided by the Insurance Institute for Highway Safety shows he Fiat 500 during a crash test. The agency says the Fiat 500 and the Honda Fit were the worst performers of the 12 minicars tested in terms of potential injury to drivers. (AP Photo/Insurance Institute for Highway Safety)
This undated photo provided by the Insurance Institute for Highway Safety shows the Chevrolet Spark during a crash test. The Spark is the only minicar tested to earn an acceptable rating in the small overlap front test. (AP Photo/Insurance Institute for Highway Safety)
This undated photo provided by the Insurance Institute for Highway Safety shows he Honda Fit during a crash test. The agency says the Fit and Fiat 500 were the worst performers of the 12 minicars tested in terms of potential injury to drivers. (AP Photo/Insurance Institute for Highway Safety)