Garageman, not garbageman, and it's probably the first time the man who mans the pumps and services the engine has been so called. He's a natural guide, however, for a quick check-up of the car's condition, a closer look at what makes it go. Much of this information is found in Scott Corbett's book of that name, among others, but this is briefer and more simplified and the parallel to a (Negro) boy's bike is apt (though his hair flying back in the wind isn't).