Is waxing a car a good idea?

It is a great idea, if you want to protect the paint and make it look new. Years ago, they put a clear coat over paint to help protect it, but this only lasts so long before it begins to deteriorate or show signs of wear.

At least once, but ideally at least twice a year, get a simple polish or wax to protect the paint/clear coat. For your average car, it takes about an hour to do. Good Luck!