So is this one of those "you have no rights in an automobile" rulings? I do recall that the Supreme Court has never been friendly to individual rights of anyone in a car.
What part of "The right of the people to be secure in their persons, houses, papers, and effects, " are they missing? A car is certainly an effect, and is a portable abode (house). It can be thought of as an extension of the person.
I've never heard of anyone mowing down innocent bystanders while being drunk in their homes. (RV's excluded)