Two U.S. senators have asked the world's biggest automakers for information on steps they have taken to protect cars from being hacked, as attention on vehicle security has surged following the first car recall over a cyber bug. U.S. Sens Edward Markey, D-Mass., and Richard Blumenthal, D-Conn., wrote to 18 automakers today asking about efforts they take to secure their vehicles, including 2015 and 2106 models.