I don't rent from Hertz Norway to often but Hertz in the Nordics usually holds a very high standard on their cars, especially at locations in big cities and airports. By high standard, I mean pretty much loaded and I have yet to receive a car older than 6 months. With that said upgrades are rare but they do happen(especially if you book an automatic car). Cars you might get instead are Volvo's with a lot of options or fords. I have seen one or two BMW's and a tesla.

Hope this helps a little