Auto body repair & detailing: body refinishing, body side moldings, car repair shop

Question
I had a minor parking accident with my two week old GM car which removed the paint on the back door. The GM dealer quoted $1000 to refinish, including minor dent, but a second quote from a well recommended repair shop was only $500. Are there special techniques available to large GM dealers that might not be available to a private car repair shop, that would jusify the large price difference?

Answer
If you like the work of the cheaper shop, then take it to them. GM may have quoted  a price that included removing door handles, body side moldings, and the belt strips. This costs more, but the repair is nicer, and lasts longer. This is important with a new car. Maybe the other shop is low on work, and wants the job more than the GM shop. It's hard to say. Bill