The refinance process is really quite easy.    Most of the time the new creditor takes care of paying off your old loan, you keep the car in your possesion the whole time.

Yes, Cap1 is reputable for refinancing auto loans ~ they pull all 3 CRAs however.   You could also try with a local bank or CU to see what they say.  

Hopefully you can get that 18% rate knocked waaaay down....Good luck !