Car sizes, in reality

Problem is that the next step up from 5-passenger is 7-passenger, and renting 2 7-passenger vehicles would be overkill for your group. Unless the 6 kids are all teenagers, I think 2 5-passenger vehicles will work fine for you.

One way to get an idea of the car's size is compare it with a model sold in the U.S., like a VW Golf, which is sold here as a Jetta. Ford Fiestas & Focuses are the same, too, I'm pretty sure. I saw some pretty optimistic luggage & passenger numbers listed by the rental companies when I was looking the other day.
I don't think you would have a lot of trouble driving a 10-passenger van around Tuscany unless you spend a lot of time in cities. Maybe someone with experience in that could give you some advice.

Hi Megan Great you are taking the kids to Italy! IMHO, a European sedan will NOT be sufficient to take 5 people of any size with luggage. I think the car rental guidelines are absolutley on target with sizes. Try to find a car in Europe that is similar in size to a US car. There are some Euro brands that are sold in the US. Then find one even if you have to go to a dealer. Think Mini Cooper. Or I think the rental sites also offer dimensions. Measure against any sedan. Car and hotel room sizes are so so small compared to the US. And you need to see a Euro car here. You will get it once you arrive. But that is too late to make a switch since station wagons and mini vans are in scarce supply. Also get automatic or you will be very sorry unless you drive one now. Also, if you have a GPS at home, buy the Euo maps or get one at a discount online. Easier to use the GPS you already know than learn a new one. Also buy Michelin maps as well online at Barnes and Noble. Both are important. Usually, luggage space is minimal in any Euro car. So 5 pieces of luggage plus some backpacks is a lot. And it is very uncomfortable to carry you stuff on your lap or under your feet for long stretches. Also you can check if station wagons are available. Also very small but at least bigger. If you want this or mini van, make sure you reserve at a major rental site like airport. Often there is little selection at the smaller cities or even at the rail stations. AND no guarantees. I would check the pick up spot to confirm the rental car for the bigger cars altho not sure how much that will help. A week in advance. Heads up. Leaving luggage in the car is a come on for thieves in Italy. Not sure how you manage that. Altho some people say, put an Italian newspaper in the car. Bobbie

We just returned from Italy. We rented a VW Touron, a small SUV. It was comfortable for four adults with four 21" rollerboard suitcases and four backpacks. It had a cover to hide the suitcases. But it was a tight squeeze in many of the small parking spots you'll find in the hill towns of Tuscany, so forget a van... We picked up the car at the Termini in Rome. We also rented a GPS as it was more expensive to download maps and bring ours from home...but I agree, it would probably be easier to use your own...and you'd be guaranteed to have it.

"But it was a tight squeeze in many parking spots." I'm guessing that might be a bit of an understatement. :)

No kidding! 1 driver and 3 to supervise!

We were thinking of renting one 7-passenger and one 5-passenger, or two 5-passenger cars. The other family traveling with us has 2 kids and we have 4, so we thought between the two vehicles we could fit all the luggage and children. Two kids (one in each family) are in car seats, which takes up extra space in any car. We won't be keeping any luggage in the car, since we're staying near Siena in a villa and will be using the cars mainly for day trips and to get back to Rome for our flight home. We are currently looking at renting at Fiumicino airport. Any other suggestions are appreciated!

Megan:
I am a big fan of Internet reservations, but this is a situation where some professional assitance might pay off in addition to all the on-the-ground advice you are receiving here. Check out http://www.gemut.com. They are a very nice family business, and once you submit your request for quote online, you will be contacted and will have to call to confirm all of your arrangements. It is very personal that way and in this case, Andy can give you some good advice on options. And I found they beat the quoted prices of both Hertz and AutoEurope online. (You might get the impression from the site that they only do rentals in Germany, Switzerland and Austria, but they can make arrangements in all of Europe. Worth a try! What a fun time your families will have!

Sorry Bobbie, but I have to disagree about renting an automatic if you drive one here. If you know how to drive a manual, they are MUCH cheaper than an automatic. Of course if you can't drive a stick shift you don't have much choice.

Andrea Yes, I should have mentioned that automatics are more expensive.
However, trying to drive in European cities with small streets, hidden street signs, round abouts, etc i s very difficult, without also having to remember how to drive a stick shift. Lots of stopping and starting. The friends who rented stick shifts were sorry they did. Fine, of course on the straight aways. Bobbie

Having done this recently, maybe this will help. A 5-series BMW (or comparable) will hold 5 adults, 5 rolling carry-on size suitcases, and 5 smallish, stuffable shopping bags, and not much more!