I was promised a Mercedes Thunder or a similar class vehicle, but was given a Fiat. How is a Fiat considered the same class as a Mercedes??? Moreover, this Fiat only has one door on the right side in the rear; there's no door on the left side, so you can only enter from the right. The first seat you encounter is broken (the seatbelt doesn't work). Seriously, I'm baffled. How can they rent out a car like this?

Quite good

The rental company had a guide who was very polite. However, the person who assisted me during the rental was not very professional, especially since he kept speaking Italian to someone else while talking to me. Most importantly, I ended up paying almost double the rental fee, which was very irritating.

Avis is considered a high-end rental company, there’s nothing to criticize.

The staff at the Rome airport counter spoke very poor English, hardly understandable. They kept pushing for full insurance, and seemed very displeased when we declined. They gave us a subpar car despite our large luggage. At the parking lot counter, they kept stalling and refusing to change the car, only offering a FIAT500 convertible, which was a struggle to fit our luggage into. I was quite dissatisfied with the service attitude of the Rome airport staff, but to avoid affecting our itinerary, I didn't argue further.