Confused. The title of the thread never said costcotravel.com. It just said Costco for car rentals - seems to be cheapest always! ...

Using a cashback site with a non-Costco discount code would probably would have been more expensive.

Then again, that's the whole point of comparing. If renting in Germany for a weekend rental, Sixt probably beats everyone hands down.

During peak holiday season, my Sixt and Hertz corporate code would beat everything out there for US rentals. Other times, the Costco code (regardless of how you book it) is a darn pretty good code.