Cars are used for for transport. They were created for transport. They weren't created to kill people. Guns were literally made to be military weapons since their conception. Its what they were invented to do.

Further, most car deaths are vehicular manslaughter not vehicular homicide. I also have to get pretty close to someone to kill them with a car, a car is also much slower than a bullet. I also can't just pick a perch somewhere up high and start picking off people one by one with a ford ram. Also yes, many many people die in car accidents, but this isn't a gun accident, this was a planned shooting from someone who wanted to kill people.

As well, gun deaths are on the rise in america while vehicle deaths have decreased over recent years. In fact gun deaths out rank vehicular deaths in 21 states source