2002 impala warm up in winter

Modern engines do not technically have a warm up period. In the old days it was a necessary step. However, its still not a bad idea to let it idle for a minute or two. That will give enough time for the oil to circulate and coat the engine internals really well. But the basic answer to your question is: It's not required, but it doesn't hurt. If you have to jump in the car, start it, and go, you're not hurting anything.