I've never heard of 'cruiser' being used to refer to a plane, either. I think the reason Matthew's link provided all those results, is that in each of them (or at least the few I randomly selected), 'cruiser' was part of the plane's model name.
I think you'll probably find some results for cars as well, but again that's just part of the name. I remember about 10 years ago, (give or take), when the
Chrysler PT Cruiser hit the market and was all the rage. (I find them unattractive, but that's just me.)
People probably use the term 'cruiser' in a model name to imply that the vehicle in question provides a smooth or enjoyable ride, as opposed to just being utilitarian.
Otherwise, unless it's actually part of a model name, I've never heard the word 'cruiser' used as a synonym for anything other than a ship.