What a hoot! And just what I was looking for, too!

The book I think I've finally lit on is The Night the Heads Came by William Sleator. Kid helps best friend (both in their late teens) to run away to art school. The fateful night, the two boys get in our hero's car and start off for the school. Our hero wakes up in the car, which is off the road but undamaged. His friend is gone, he himself is uninjured, but has no memory of the events of the previous night except that he was driving his friend to art school. Our hero is naturally a suspect in the disappearance, but it turns out that his friend was abducted by aliens, who are doing surveillance because they suspect that another alien race seeks to conquer Earth. Or is that just a sham tale to cover their own plot??

So -- is that an aluminum foil hat story or what? ;)

Thanks again--
Mary Anne