A used Toyota Camry is the ultimate sensible choice. It runs forever, sips gas, and costs very little to maintain. If you shop at the end of December, dealers are desperate to hit year-end quotas, which means you can negotiate a much better price on that $18500 sticker.
To pull this off without draining your savings, we need to split the cost. Use your negotiating power first, then deploy a card like the Discover it® Cash Back to handle the down payment or a chunk of the price without immediate interest.
The 15 months window is a hard deadline, not free money. If you still have a balance on your Discover it® Cash Back when those 15 months end, the standard variable APR will kick in on the remaining amount, wiping out your interest-free savings.