Don't listen to your dad anymore, at least if you drive a new car.
Forget everything you were taught as a child. Okay, by "child" we mean 16- or 17-year-old and by "everything" we mean warming up your car before you start it. Keep the other stuff, such as how to hold a fork and use a toilet. Chances are a new 16-year-old driver will be driving a used car, and in some cases (no specifics here) said car will be potentially 10-15 years old. According to Sharon Profis of CNET, warming up an older car for a few minutes is fine. However, warming up a new car for anything past one minute is a waste of time and hurts the environment.
Profis gives a few scenarios where the practice of engine warming should be taken out and dusted off, but for the most part it sounds like it should be consigned to history books.