I made a reservation for Avis in Zurich, Switzerland at the downtown City location via the US website. Using the Rental Car Momma discount code (D454000), I was able to get a quote of $419USD for an 11-day period. This is about $50USD less than with other discount codes or rental agencies (i.e. Europcar).

At the time of final reservation, in the detailed charges section (under the described surcharges), was the following text in RED:

Additional surcharges (some of which are mandatory) may apply to this booking.

Has anyone encountered this before? If so, what surcharges are they referring to? I'm concerned that, ultimately, the car is going to end up costing us MORE than if we rented from Europcar.