I don't know if a car paint shop would do powder coating. I googled a bit to find an answer to your question and found that is powder coating is done on parts of cars say, the engine brackets or wheel rims but not on the body panels. Powder coating is brittle and shear lines would appear with dents and gravel strikes. The wrought iron hand rails on my front steps came powder coated instead of paint. They are guaranteed for 10 years. I was painting the old rails yearly and they still rusted through. My treadle irons are jet black and shiny. I love them.