funny, my daughter (8) asked me this 2 days ago and i struggled at first but think i finally got all 20 of them (forgot the 911 on my first pass):

1. 1972 Toyota Corona (not the typewriter)
2. 71/72 Maverick (welded 2 wrecks together)
3.1972 Super Beetle
4. 1961-69 VW Beetle with rag sunroof (built from junkyard and my 72 engine)
5. 1st Gen. Scirocco
6. Ford Fiesta
7. Toyota Cargo Van
8. 2nd Gen Scirocco
9. Honda Accord (does it really matter what year?)
10. VW Jetta " "
11. Jeep Cherokee
12. Jeep Cherokee (limited...wahoo)
13. 97 Jeep Grand Cherokee (finally got a V8)
14. 87 911 Targa
15. 92 BMW 750IL (Lead sled)
16. 98 Crown Vic (don't ask...came with mirrored shades)
17. 99 Ford Explorer Sportrac
18. 2001 Audi TT Coupe
19. 02 Jeep Liberty
20. 2002 Mercedes CLK 55 AMG
21. 1999 Isuzu VX # 1397

I think that gets everything 'cept for bikes and boats (didn't count the wife's cars since they are dull and i rarely drive them)
17.