depend alot lf the imformation even exist.
most popular is Car example
year:1970
Plymouth E body types Barracuda, Cuda, Grand Coupe total production 48867
roof type: HT, Coupe, Convertible total convertible production 2501
most popular 1 of 1's are hemi's 14 hemis in verts
and then rarer usually: 4 speeds 5 4spds
most of the time the rare cars are mostly know to exist and a guess off of how many were painted in the color
a good data base suck as Galan Govier has imformation on a huge number of vehicles or a chart such as these.
most popular 1 of 1's are based of Car, style, engine, tranny, and paint color.
here is a chart
http://www.440magnum-network.com/info/tech/1970barracudatotals.shtml