Well, $15,000 ain't gonna buy you much new, and you have ruled out, like, 90% of the potential candidates.
My vote is for slightly used. Buy an extended warranty if you are worried about stuff like that.
I like suggestions as Camry, Corolla, etc. If you want cheaper, Nissan Sentra can be had all day long under $15k. Chevy Cruze is a great choice. Ford Focus for the prized "driving dynamics", although try to avoid the PowerShift trans. All these cars will deliver solid fuel mileage, good reliability, and low cost of ownership.
Originally Posted By: yesthatsteve
CPO Prius is probably also worth a look. Hatch, cheap to insure, great fuel economy and reliability, and you can probably find a few in your price range in an area as large as Houston.
This is my favorite suggestion. The used market for hybrids/high fuel mileage vehicles has absolutely tanked. Some aggressive shopping should turn up plenty of Prius's, Chevy Volts, Nissan Leafs, Civic hybrid, or whatever at deep discount pricing. A Prius would be perfect for what you need.