For a French van rental: We can find plenty of vans that seat six, but will not also handle six suitcases plus carryons. Has anyone had success in finding a roomier van than offered by the popular rental agencies? The Chrysler/Dodge vans with Stow & Go compartments work, but so far we're unable to find in Europe.
Don't know. Another alternative would be to have a little less luggage. Or a roof luggage rack for storage/
Another option is to get one with a tow hitch and a tiny cargo trailer. Very small cargo trailers are relatively common in Europe since they make the most use of smaller vehicles.
Peter:
In October 2007 we were a party of six and we had the same issue. Renting through gemut.com (an American company specializing in European car rentals, airfare, etc) we got a Chrysler minivan.
We packed very light - each of us had one small carry on size bag (and also the three women each had purses the size of a Samsonite!).
The luggage space in the minivan with the third seat in (which we obviously needed) was extremely small - we could fit about half the luggage there. On the first day we just crammed everything inside - the next morning we found some bungee cords at the gas station and strapped the luggage on the roof rack - we looked a little like the Griswolds rolling down the road but it worked fine.
Of course our itinerary was such that we did not have to leave the van anywhere with the luggage on the rack.
Lastly, at one location - with the luggage on the roof rack - we were unable to fit in the medieval village gate - we were too tall! Have fun.