I saw a purple Firebird today and thought wow you rarely see a purple car (it was very purple), but then as I began to pay attention while driving around I noticed a lot of different shades of purple. That led me to wonder - what is the least common color on a new car from the factory? Not a specific model, like a lime green Challenger, but overall the least common color to be found from any manufacturer. For purposes of discussion colors should be grouped by the primary shade - like neon green and lime green are all shades of green, and green isn't that uncommon.
I don't think it is purple, although that particular very purple shade is unusual. I think it is orange. You rarely see any orange cars, especially if they are not reddish-orange. What is more uncommon than a true orange car?