There are car services, they are just generally operated out of Atlantic City, New Jersey, Berlin, or London, or a junkyard somewhere in Italy. There are a number of people in Rome who have a car and they make their living that way. Generally a BMW. They don't work for a car service. They are independent.

Somebody goes to an app like Groundlink, Execucar, Roma Limousine, or whatever, none of which are located in Italy, and that app's website person sends out a blast text to all of the independent drivers. They are all apps run by a couple of dudes who have never set foot in Italy. It is not possible for one car service to be better than another. That is a complete misconception of how the car system in Italy works, with only a few rare exceptions. They are all using the same drivers.

There actually is a company in Positano that has it's own five cars. It's owned by 2 brothers. Other than these rare exceptions, there is no car service. You just go to any website, and they will contact one of the 500 drivers in Rome. Whether they show up drunk or sober has nothing to do with the website you choose. They are all the same drivers who link themselves to all of the same apps, more or less. You can book a car from five different apps, and you will still probably get the same driver.

No one can help you with the fare cost guess, because you are still keeping when you are going a secret. Prices can triple based on if you are going before or after Xmas.