That glossy finish looks great now, but keeping your car's paint alive through winter is a real battle against road salt and grit. A professional ceramic coating locks out the grime, though it usually runs about $1200. Doing this right before the salt trucks hit is smart timing, especially since some detailers drop their prices a bit when business slows down for the cold months.
We can break this cost up, but remember that financing is just for smoothing out the bill, not cutting it down. You still need to negotiate the price of the job itself before you ever talk about how you are going to pay for it.
That 0% intro window is a hard deadline, not free money. If you still have a balance left when those 15 months run out, you will get hit with interest on the whole original amount, so make sure your monthly payments cover the full cost before time runs out.