I'm wanting to machine polish my car over to remove some scratches and swirls etc but a friend has told me it's not possible on metallic painted cars due to the lacquer. Is this correct? thanks andy
Nope, its not correct. You can certainly machine polish metallic paint. I have anyway If you aren't familiar with machine polishing though I'd do a bit of research on detailing before you attempt anything.
I'm going to attempt machine polishing this weekend for the first time, there is a good write up at polish bliss: What Polish Should I Use? | Car Care Advice | Polished Bliss