Actually a heat-gun style hair dryer is the best of all. Will allow you to hold right on the key hole, or go around the door perimeter when you are dealing with really nasty ice. Not really hot enough even on high in cold weather to harm paint, rubber or glass. Have used it to get ice on the windshield started when anything else would have done nothing or cracked the glass.

Oh, and the last one cost me a $1.50 at the thrift store!!

__________________
1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150