Exactly, I did that a while ago.
Jan 08 Car sales/dealer
Ford 4.0
Chrysler 8.7
GM 16.5
Toyota 27.3
Sales are easy to get from Sir A's figures, dealer #'s are harder to find.
No dealer can survive selling 4 cars per month
In January 2008, Ford sold 12 372 vehicles(Ford the division, only)
Chrysler group sold around 17 000
GM sold 26 500
Your numbers said Ford sold 2862 cars.. which isn't far from the truth, but you forgot to consider the LIGHT TRUCKS.
Also, since when do people generalize the entire year with January numbers? Winter months have very low sales numbers, let alone a good car/vehicle ratio.
There are way too many flaws on this document. I suggest you clear out that waste of hard drive memory.