How about a Camry LE? You can get them for 18,000 with 0% financing.
Or a Camry SE for a little bit more fun
I rode in my friend's Camry LE 4 cylinder. It was suprisingly smooth.
He also had it for 2 years and it looks clean and streamlined in the interior.
The transmission is also very smooth. The ride is quiet and smooth, too. It's also roomy and dependable. If you don't think you're going to keep the car for long, the MPG probably wouldnt make a difference in your budget. It still gets 23-33 mpg.

A Prius a day keeps the doctor away!