It's not a huge picture either: 82 cm high by 60 cm wide. The mirror on the back wall is only about 5" wide on the canvas yet it's a detailed picture within a picture. The brush used must have been just a single hair.
I once watched an amazing documentary which went through all the details of that painting and another similar one.
That is fabulous & correct me if I'm wrong, but it's a 1968 Chrysler 300 convertible. Here's the 2008 version...