Dear Tom and Ray: My son, 16, bought a ’77 Pontiac Grand Prix. It’s loud, with a big motor (muscle-car-type motor, original everything). Anyway, he sawed off the exhaust pipe to make it even louder, ...

There's a lot going on inside your vehicle at any given time, whether you're idling at a red light or driving at freeway speeds. Much of this activity involves chemical reactions that — while ...