Originally Posted by
crhptic
A one-way of that length is difficult to do cheaply as you are putting a large # of miles on the car and leaving it far from where it started. Unless the car company has some particular desire to move cars that distance, I doubt you will find a really cheap deal for 2 weeks of an SUV and that great a distance. I suggest trying any/all discount codes in this thread, and checking all US rental car companies using good discount codes for the others as well. (You can find these on FT for almost every company)
+1. Darientes should try travelocity.com to view all rental co.s at once. Also do without a car while in Chicago & pickup in downtown Chicago if s/he will be staying there a few days. Rate may be lower (or higher) than ORD pickup.
Given the distance you are traveling you might also want to look into Auto Driveaway.
Trouble with Auto Driveaway is that they require U to drive steadily > 400 miles/ 644 km per day with minimal deviation! Good for someone who wants to make short stops--service clients for a half or full hour each in a bunch of towns along the way, but not for sightseeing & appreciating the USA!
Finally, remember that Chicago to L.A. is about the same beeline distance as Dublin to Moscow or Athens!