Go to www.autoeurope.com or www.kemwel.com, a broker/consolodator which works with major compampnies such as Hertz, Europcar, Avis Budget, etc.
Actually it is the same company after AutoEurope and Kemwel merged years ago, however they retained both websites. Prices may be similar. I also usually select the NO DEDUCTIBLE insurance coverage also (an extra $5 or 6 per day), for peace of mind, since deductibles are generally 1,000€ and a small scratch is enough for them to charge you hundreds of euros for damages. Your credit card may be covering the deductible but you have to deal with the paperwork to get reimbursed by your credit card in case of damage.
There are many categories of cars you can choose from, such as (in order of increasing size):
MINI
ECONOMY
MIDSIZE
LARGE
WAGON-SUV
VANS
The Fiat500 belongs to the Mini category and so does the Fiat Panda sometimes.. I never go for that category for me and my wife. They are too small with no power and little cargo space.
The Economy category would be sufficient for two people, especially if you don’t pack huge suitcases. In any case you can also fold the back seats to increase the cargo space. Typical cars in the Economy category are the Opel Corsa, the Toyota Yaris hatchback, the Peugeot 208.
I generally choose the SUV/WAGON category or the Midsize category (you get the same type of cars either way). In that category I usually end up with a Jeep Renegade, or Opel Mokka or (if I’m lucky) the Jeep Compass. In the past I also got the Fiat 500L in that category. That Fiat model is out of production so now you are more likely to get a Fiat500X, a crossover Compact SUV. If you select Sixt company, it is likely that category might be a German car such as a VW Golf or T-Cross.
Although an Economy size might do for the two of you, however I recommend you select from the SUV/Station or Midsize category. It is not much more expensive than an economy but will give you extra power and space. Also the Economy cars don’t usually come with auto transmission, in case you don’t or can’t drive a stick.
Even in the midsize category, you won’t actually get a US size midsize car, those models are all small compact SUV crossovers that are still easy to drive in the narrower Italian roads.
The Stellantis Group is big in Italy. Since Fiat500X, Jeep Compass, Jeep Renegade are all manufactured in Italy, the chance of getting one of those is very high if you select that size category. Since they are made locally they are very popular models in Italy, and rental companies like to fill their fleets with autos that are easy to sell in the used car market. If at the desk you have a choice among those 3, I would go for the Jeep Compass. It has the largest cargo space of the 3. I ended up with a Renegade at the moment (Italy is full of Jeep Renegade and Compass). I can fit one midsize suitcase, two carry on size, and two small backpacks in the trunk. With the Jeep compass last year I had two midsize suitcases and two carry on backpacks. The Opel Mokka is about the same as the Renegade. I had that too last summer 2023.