Do we need a car for our Rome, Florence, Venice trip?

No- all easily done by train.

If you are planning to spend time in Tuscany countryside a car is useful but with 6 people you would need a van to hold all of you and your luggage and a van would be more of a problem than not- parking, narrow roads, etc.

If you share more of your planned itinerary we could offer more specific advice

All three cities are not car accessible. Venice of course is famous for not even having roads. Rome and Florence have restrictions on cars in the city centre ("ZTL" = Restricted Traffic Zone = Residents only), and have no parking at any of the places you would wish to visit, nor at most hotels.
Plus one of Italy's main High Speed rail lines is Rome - Florence - Venice (300 km/hr).

The only reason you might need a car is if you are also visiting rural areas and small towns, and only for that part of the trip. Definitely no car if just visiting those three cities.

For a beginner's guide on Italian trains, read here: https://www.seat61.com/Italy-trains.htm

You can look up times and buy tickets on the Italian Railways website: https://www.trenitalia.com/en.html
Tickets are cheaper if bought in advance (1-3 months)
You need to know the "real" (Italian) names for the city centre stations: Roma Termini, Firenze S. M. Novella and Venezia S. Lucia

No need for a car at all if you are only visiting these 3 cities. We are currently visiting these 3 cities with our granddaughters and exclusively traveling between the 3 by train. We purchased our train tickets ahead of time to save money.

Our apartment greeters appreciated knowing when our arrival time would be in each city to facilitate our check-ins. It’s been easy and stress free.

Dear Hadden -

A lot depends on your desired activities in those cities + how comfortable you are with public transportation. As long as you do not mind taking busses and trains, you should be okay. Your selected hotel/places to stay may not be near bus stops or train stations. This may require walking/taxi cabs. But again - this can work.

Sorry that this doesn't answer every question, but best I can do with a general question.

Hope you enjoy your trip to Italy!!!

Very few regulars on this forum rent a car in Rome (or Venice since it doesn't have roads).
Florence is also not car friendly and the only reason to even think about renting a car there, would be if you're going to rural destinations in Tuscany without regular train service, and even then you would only want to rent a car on your way out of Florence to those destinations.

Just to emphasize what Chris F said. It's not just that you don't need a car for these cities; you don't want a car.

If you have a car, it will be a very expensive headache. You will have to park it outside the restricted zone (figure €25 or more per day), since you can't drive it anywhere near the centers of Venice, Florence, or Rome. You will then have to take a taxi or bus from the parking lot to your hotel. If at any point you drive into the restricted zone - even by accident, and even for just a short bit - your rental car's license will be photographed and you will subject to a fine. And, the fine comes in installments. First, there's a fee from your rental car agency, for turning your information over; you agree to this fee in your rental car contract. This fee used to be reported as about €45, but a recent report here had much higher fee. Then, you get the ticket itself, months after your trip, and this ticket is for €100 or more. Then there are the speed cameras on the causeway into Venice; people report that going even a small amount over the (low) speed limit triggers yet another two-stage ticket.

So, as Chris said, if you're just seeing these cities, don't even think of renting a car. From the train stations, you can take a taxi or bus (or in Venice, the vaporetto - a water bus) to your hotel. Once settled, you'll walk, bus, taxi, or vaporetto to get everywhere. Remember these are very old cities, and the parts of interest to you as a visitor long predate the car.

If you can commit to taking specific trains, you can save a bundle by buying the tickets in advance. The cheapest tickets can sell out, so if you do want these, you'll want to buy them when they go on sale (I forget if that's 90 or 120 days in advance). However, the cheapest fares are non-refundable and non-exchangeable (or have significant restrictions on these actions). If you're not as sure of your plans, you can buy full price tickets at any time (either in advance or on the day of travel). On these routes, all tickets - bought online or in person; bought in advance or day of travel; and discount or full fare - will have a reserved seat. You just get on the train, find your reserved seat, and relax for the relatively short ride (1.5-2.5 hours).

hadden,

One other thing to be aware of is that each driver listed on the rental contract will require the compulsory International Driver's Permit, which is used in conjunction with your home D.L. IDP's are easily available at any AAA / CAA office for a small fee, and are valid for one year. Whether you're asked to produce an IDP or not, it is the law! You could face more fines for "failure to produce" and in that case, the fines will be collected on the spot".

The others have covered the ZTL and speed camera issues, so I won't elaborate on those.

No, No, No, take the train.

No.

The key here is that you can’t use it! Let’s say you stay at a hotel near the Vatican (randomly picking an area). You finally found a hotel that offers parking at a HIGH cost (most hotels in the center don’t have parking). So you have you car. You want to go to the Colosseum today. Great. You can’t drive there. No parking, car free zones on the way. So you take the bus, metro, or cab. Later you have dinner. Decide between 2 restaurants - either a few blocks down the street so you walk, or near the Trevi fountain on a car free street with no parking so you take a cab.
Repeat every day. The car doesn’t get used.

Same for Florence and Venice even more since...there are no roads!

Rome to Florence is s 3.5 hour drive or 1.5 hours on a train. I don’t recall Florence to Venice but it’s also a fast train, faster than driving.

Also - hotels with parking are often (in Venice’s case always) out of the city center. That makes sightseeing difficult and prevents you from going out for evening dinner, drinks and walks in the historic center, going out early to avoid crowds, taking a mid-day break to avoid crowds...in all ways staying in the center is best and that’s precisely where cars are the most useless.

A car is useful for small towns and countryside visits. You could rent one for one day if you wanted a day trip like that - but even then there are trains or busses to smaller towns.

A car has always been useful to me in Venice. I bought it used from James Bond.

Just finished this same trip. Venice, Florence and Rome with a family of 5. Did not need or want a car in any of these cities. Venice and Florence are easy to get around on foot. In Rome we used the metro to get to other parts of the city such as the Vatican, Trevi Fountain, etc.

To add to my previous comments, no car can (legally) travel as fast as the high speed trains at 300 km/h. All of those cities are served by high speed rail so train will be a much quicker, more relaxing and pleasant journey. You'll actually be able to enjoy the scenery instead of keeping your eyes on the road, and will arrive in the centre of each city.

If your itinerary is Just Rome-Florence-Venice (and a few close neighbors), a car would be a nuisance. For a group of six, after adding in the up-charge for a vehicle with the space needed for all plus luggage, fuel, parking, tolls, etc., train fare would still be more cost effective. Leave the driving to Trenitalia and Italo and enjoy yourselves.