This question gets asked a lot, unsurprisingly. In a way, the answer is why do you own a car? The advantage is flexibility. The flexibility to go where and when you like.
Europe is almost made for driving. There’s no question that it also has excellent public transport, but the road system is also of the same quality. Europe is also smaller than you think. To travel from Venice in far eastern Italy to Paris is 1100 km, takes 10½ hours and is freeway all the way. To put it in perspective, Melbourne to Sydney is close on 900 kms and few people would baulk at that trip. The French Riviera to Paris is less than the Melbourne to Sydney distance and takes about 8 hours. In terms of cost, the car would run 110 € for fuel and tolls. Add in the cost of the rental at 50€ for a total of 160€. A ticket on the high speed TGV is approx 95€ per person and you’ve got the hassle of getting to the station from the hotel, maybe by taxi (extra cost). Tickets can be got for less, but this involves pre-purchasing. In terms of the journey itself, in the car you have the opportunity to divert off the road if something attracts your attention. On the train at 300 km/h, you can’t see much at all and there are only 3 stops between the Riviera and Paris, so you’re locked in.
In choosing between car and public transport, there are a few issues we have to consider. Firstly, for cars, you need to choose between straight out rentals or leasing a vehicle from one of the French car companies. For lengths of less than about 12 days it probably is slightly cheaper with the rental option. There are restrictions on some vehicles though. For example, if you rent a larger car like a Mercedes in France, it can’t be taken out of that country. Leasing the vehicle becomes much more practical if you’re there more than 2 weeks and you want to travel outside one country (and who doesn’t?). You also get either 7 or 9 extra days for free if you book before 31st March.
For the public transport, you need to be aware that the high speed services only connect major cities and you generally need to reserve seats. You can roll up at the station without a reservation, but its pot luck whether you’ll get a seat on the first train available. To get between smaller towns not on the high speed network, you’re left with the regular services, which are not as frequent and, obviously, not near as fast. You’ve also got the hassle of getting to and from the station with your luggage. In a lot of cities the TGV stations are well on the outskirts, so it’s either bus or taxi to get there. Most TGV’s run on an hourly schedule and some more popular routes are less.
In terms of overall cost it’s difficult to compare as the travel passes have restrictions not applicable to usage of cars. If you hire or lease a car, you can use it every single day, whereas with a travel pass, you’re given, say 10 days travel over a 2 month period. If we match the usage patterns, a car comes out much cheaper (nearly half the cost of the travel pass, and that doesn’t include any ancillary costs such as buses or taxis to get to/from the stations. The situation is similar with a larger group (say a family of 4) as the extra rail passes are offset by a bigger and more costly car. In raw figures, an 18 day railpass for two people is $3500, whereas a Citroen C3 from DriveEurope is $1400 for the same period. Add about $700 for fuel and tolls for the car and you get $2100, substantially less than the rail pass.
The other intangible is flexibility. To illustrate this, I’ll use the example of my friend Dominic. He and his family (two adults and three children ages 8 to 13) wanted to go to Italy for 5 weeks. He’d booked some nice hotels, some of them a long way from the station. When he mentioned this holiday to me. He was concerned about the hassle of getting wife, kids and luggage to and from the station as well as how he was going to fit in visits to attractions like Pompeii. He was convinced when I told him that Pompeii was 2 hours from his hotel in Rome by car and Salerno on the Amalfi Coast was another 30 minutes further on. He’d calculated a good five hours with rail connections and buses plus the hassle of stowing luggage when visiting Pompeii. A Citroen C4 Picasso was booked and was plenty big enough for the family.
After his return he said that the car was well worth it. The flexibility of having the car at the hotel meant you weren’t tied in to ticket reservations, public transport or bus schedules. The only problem he had was with being ripped off buying railway tickets for the Cinque Terre!