I stink at this game too. It's pretty tough especially once you get to the tougher races. I know the NA Tune up works well to give you more horsepower. And if you earn new, crappy cars, sell them off quick to get more money. Other than that I can't help much.
[quote name='"Toxicshock23"]I used to be really good at it(the start of the game)' date=' but now I can't win any races I could before. I really do suck too.[/quote']
That's the same thing that happened to me, I did good at the beginning but then it gets hard as crap.
I just played it for about 6 hours and got way farther. I souped up my Supra Twin Turbo(got it up to 500 some horsepower). I got a ton of cash with that(won a car worth over 650,000). Anyway, I also unlocked/bought the Ford Concept. I souped it up and now I have 719 horsepower.