If you're from the USA, renting a car is advisable from www.AutoEurope.com or www.Kemwel.com, sister companies. You'll pay about the same amount to rent a car for 1 day as you would for 3, so you might want to consider that. Yes, you should absolutely rent it ahead of time and expect that the longer out you rent from your travel date the cheaper it will be.
The cost per day depends entirely on what class of car you rent - varies enormously, obviously, whether you're asking for a Renault Clio or a Mercedes. And whether you rent a sans plomb or a diesel. And whether you rent a manual or automatic.
Typically, the minimal rental time should be 3 days to get the daily rate to go down. 1 or 2 day rentals don't make sense economically or in terms of time investment to pick up and return your car.
Autoeurope can be used by anyone, not just Americans.
Rent a diesel car to save gas. Prices aren't too different between diesel and gasoline these days, but diesel gives you better mileage. Unless you are a race car driver, you really won't notice the different.
Renting a manual shift is much cheaper and guarantees availability. Automatics aren't always available.
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