And also new to me on the ADR site on its "To and From Fiumicino" page is: Chauffeur-driven car rental
Car rental with chauffeur - Aeroporti di Roma
Here's a cut and paste
A chauffeur-driven car rental service is available in the area in front of the airport exit, marked by the NCC sign (noleggio con conducente - rental with chauffeur). The service is provided in generally blue or grey coloured cars, for which variable, destination-based fares are charged. The service should be requested in advance.
And then it provides the name of 3 companies with linked websites. I looked at the first two trying to find pricing, but didn't see any details. However, the third company shows prices for a Mercedes E Class from €45
https://limousineuara.com/en/transfer-2/
I've never come across any of these companies before. Have any of you? Are these companies different than the car services we've discussed in the past? The way they're listed on ADR's site makes them seem more sanctioned than the ones in the wiki above.