Owning a car is a slow leak of small repairs until something major like the brakes goes out and demands attention right now. When you hear that grinding or squealing, you know the job can't wait, but paying full price at the mechanic hurts. The trick is timing your parts purchase for holiday weekend auto sales when markup drops and online retailers slash prices on kits.
You should shop around for the best deal on the hardware first, keeping financing separate from the price tag. Once you have the lowest price on the parts you need, you can figure out how to pay for them without draining your checking account.
Remember that the 0% intro window is a strict deadline, not free money. If you still have a balance left on the card when those 18 months are up, interest will kick in on the original amount from day one.