Been through IAH a million times, but never actually stopped there... that's about to change.

Couple of logistics questions about rental cars, etc... is there a big combined rental car center, or are all the companies in separate locations? How often do the buses (or whatever) run?

On my way back, I probably have a relatively tight window for time, so I'm trying to figure out how early I need to be at the airport to turn in a rental car, check one bag (as a Star Alliance gold member flying CO), and get to my flight (a CO mainline 737 going to RDU)...

The flight back is at 7pm on sunday night, if that matters. I'm trying to figure out if I can show up at IAH at 5:45pm and still have a reasonably good chance of catching my flight... rental car return time, time to get to the terminal, time to get through security, etc...

any help is greatly appreciated.