SUVs are built for utility, but the interior takes the most abuse. Mud, snow, and spilled coffee eventually ruin the carpet, which hurts what the car is worth when you sell it. Buying heavy-duty liners is a smart move for maintenance, but they aren't cheap.
A full set of custom liners usually runs about $220. You shouldn't put a whole car on a credit card, but for accessories and protection packages, it can work well. If you time the buy right, you can get the gear you need without a big hit to your monthly budget.
The 0% rate is a tool, not a permanent discount. If you haven't paid off the balance by the time the 18 months are up, the interest rate will jump to the standard APR on whatever you still owe.