Uh..... Depends what you want to do really.... I mean seriously, 80s series is pretty easy.....
Use the RX7 like 69dodge said... and the skyline.. or if you can't.. just use the trueno s.s version.. max it out... it's like... easy to win like that..
Actually that's what you win from beating those races, not what I used. I used the 300ZX(two seater I think), maxed it out, and put medium racing tires on it. The race was a brease then.