Give points to the top finisher for each mfg. Base points on car count... for example 20 cars would give first place 20 pts, 2nd 19 and so on...

Rob takes 1st and earns 20 pts for ford
Glenn gets 3rd (top finishing gm) and earns 18 pts for gm

if you wanna weigh it more towards the winner give extra 1 or 2 points for the win...

It may not be perfect but I think is is better than the current system...

try it on this years results and see how each system compares..

my 2 cents...