There's no way of knowing what will be on fleet next July. The "guide" is not to be relied on. There's massive variety on the Hertz fleets across Europe - I rarely get the model that's the guide car.
Audi models in Europe , especially smaller ones such as A3, do not necessarily have nav as standard. If you have a smartphone, you can usually download maps for offline use. That's easily the cheapest option fir navigation.