[quote name='Mad39er']Used car stats are a little tricky, they're listing the stock stats for the car and not taking into account for mileage or oil. Unless you get a car with low miles on it, expect to overhaul the engine to get the stickered horsies and torque out of it but really if you end up within like 5 horsies it's not too bad. If you change the black oil that comes out of every used car, you will regain lost power regardless but not all of it if the mileage is high enough.[/QUOTE]
That's kinda what I ended up figuring out. The used car dealership shows stock HP, not the HP of the actual car they're selling you. So I guess if an oil change doesn't get you up to the stock HP, then you'd have to rebuild the engine? That's so expensive ($20k, right?) I just can't see it being worth it except for the rare/super expensive cars you buy in the dealership, at least not early on in my racing career (Level 11 right now).
I'm generally finding that the oil change, racing air filter, sport cat converter, ECU tuning, and maybe the Engine #1 overhaul are the best upgrades for your money, at least as far as getting more HP out of the engine. For between $3k and $5k, I've gotten around 30 to 66 extra HP.
I found a Honda Integra Type R Touring Car in the used car dealership yesterday for around $45k I think. That car is amazing compared to my other 30+ cars in my garage. The handling is superb, and when I eventually opt for the $20k turbo upgrade, it'll be pumping out more than 400 HP. I know it's nothing compared to the cars available in the later stages of the game, but it's great for me right now.