http://www.imcdb.org/movie_397306-American-Dad!.html
There are from all the episodes that are currently on DVD.
Some of these cars may be generic and just not resemble anything (therefore wont need to be added), but i though id put em in there in case someone with a better eye could see if they did look like something.
Season 1
Ep 1.15
Unknown Limo - 1 Star
Ep 1.17
Blue Car, Honda Insight or GM EV1? - 1 Star
Cadillac XLR - 1 Star
Ep 1.19
Francine's Car, Unknown - 3 Stars
Geo Metro? - 2 Star
1.20
Hummer H2 Stretched Limo - 3 Stars
1.21
Dodge Ram Van - 2 Stars
Jeep Wrangler - 1 Star
Pontiac Firebird - 2 Stars
Season 2
2.01
Chrysler 300C - 3 stars (Used in a quick remake of a terminator 2-esque chase scene)
2.03
Unknown Sedan - 2 Stars
Unknown Convertible - 2 Stars
Unknown Coupe - 2 Stars
Unknown Sedan - 2 Stars
Unknown truck, Peterbilt? - 1 Star
Porsche 356 Cabriolet (headlight are wrong but its definitely a porsche) - 2 stars
2.04
Saab - 1 Star
2.07
Unknown Bus - 2 Stars
Unknown (supposed to be from the future)- 1 Star
Unknown Pickup - 2 Stars
Unknown Van - 1 Star
2.08
Unknwon Hearse - 1 Star
Ferrari testarossa - 2 Stars
2.12
Made For Movie (for comments since animated Made for Movie cars aren't allowed) - 3 Stars
2.15
Ferrari F50 Spyder - 2 Stars
2.16
HUmmer H2 SUT - 2 Stars
2.17
Rolls Royce Unknown - 1 Star
2.19
Harley Davidson Unknown - 2 Stars
Season 3
3.02
Mercedes Unknown - 1 Star
Westward Go-4 Interceptor - 1 Star
3.04
Chevrolet Corvette C6 - 2 Stars
3.05
Hummer H2 SUT Stretch Limo (Slightly different to the other one)- 3 Stars
3.07
Nissan Titan - 3 Stars