There is no ECON button in the 06 like Tim mentioned.
Regarding the test drive, I can not think of anything to look for other than things that would apply to a non-hybrid car to check for. Scratches on it, the VIN is what it is listed on the Bill of Sale etc. The only thing I needed the dealer to do when I picked mine up was to take off their dealer stickers and plates that they were not supposed to put on in the first place. 