Getting ready to buy a pip and want to get 17" wheels. Are these part of the advanced package ? They are listed as part of it on the regular Prius advanced package, but I don't see it on the pip.....
F8L will probably chime in here.. he's the expert on 17" wheels and their (negative) effects on MPG.. but from what I recall, it seems to be about a -2 to -3 decreased in MPG. Of course, that depends greatly on the size, type, and brand of tire you use and the weight of the wheels.
Here's a negative for you: damaged tires from hitting potholes, with the low-profile tires that come mounted on those 17" wheels. In the 2 years I owned the 2010 Prius Model V (which comes with this "Prius Plus" wheels/tires), I had 2 damaged/unrepairable tires, to the tune of $275 each time. No thanks, no low profile tires on 17" wheels for me anytime soon. You can also damage the wheels as well, that's another $300-400 bill.