WASHINGTON, D.C. --- The National Highway Traffic Safety Administration is asking for public comment on a proposed regulation that would require vehicle rear turn signal lights to be amber-colored, according to Cars.com. 

Current law allows the signal lights to be either amber or red. This is spelled out in Federal Motor Vehicle Safety Standard No. 108. 

But the NHTSA is considering the policy change because a recent study concluded that amber rear turn signals have been proven to be 5.3 percent more effective than red signals in preventing crashes. According to Cars.com, the study focused on "switch pairs," which are vehicles that switched rear turn signal color from one model year to the next, while controlling for extraneous factors such as vehicle and driver traits. 

The public comment period for the proposed regulation will end Sept. 6.