The FF surcharge is 0.50 cents I believe. Even so, with Avis it's 2 miles per $ spent (only airport locations) so It can turn out as a pretty sweet deal. This past trip to Florida we racked up over 800 miles for a rental. Add the bonuses (2X miles) and now it's 1600 miles for what, .50 cents surcharge? Definately, not a waste. Plus the miles back in Dec counted towards Pref, remember?