We use classic cars for all of our tours. Célestine and Claudette are 1950's Citroën Traction Avants (you can read more about them here) and they are very popular cars on the road - people wave and flash their lights, and we have been in many conversations in various car-parks.
When we are out and about we often meet other classic cars or motorbikes, but that can't be guaranteed.
However, if you're really into old cars, a time to visit may be the end of April. The Loire Valley is one of the most popular places to use an older car (the roads are good quality and quiet, the scenery is excellent, and there are no steep hills) and I suspect that it will be a popular place for people to bring their cars on the new "National Day for Old Cars" on the 30th April.
If you want to spend a day in a classic car with the possibilty of seeing other cars, email us and we will investigate what events are happening in the area. We will combine that with a visit to a chateau or two for the perfect car lover's history day out.