I don't envy your position, as I've been down that road before and it hurt like hell.
Basically by the time I turned 24 I had racked up a significant amount of debt and had shattered my credit rating. Eh, young and foolish in my ways, like many of us. At any rate, about that time I decided to join the military so went in with the intent of a.) paying all this debt off, and b.) building up some good credit.
The first car I financed after a few years of paying off this debt hit me like a meteorite in the interest rate department. Something to the tune of 26%. The car was already four years old by the time I bought it, and I ended up owing far, far more than it was worth after the ink had dried. But, this was a bullet I figured I had to bite, and so I did.
After making good payments for about 6-7 months, I decided to apply for a low-risk, low credit line credit card, and got accepted. Went out and purchased (go figure) some speakers for about $200 on it, turned around and immediately paid it off. I did this a few times, then got another card, did the same routine.
As for the car, I was indeed stuck with it until it was paid off. I could have possibly refinanced, but in the end, wound up paying it off in full, got the title (at last), and now have three credit cards with a very respectable credit line, a house mortgage, two cars and an excellent credit score.
You may simply be in a situation that you have to live with for a while, if you continue to take necessary steps to improve your credit rating - focusing less on "what I am paying each month" and more in terms of "How are my actions going to affect my credit rating in the future?".
It's tough man, no doubt about it, but - and don't take this negatively - but, if you had poor credit to begin with, purchasing a $24K car right off the bat, might not have been the wisest choice given the circumstances.