I ran a C-Max 2.0TDCI for a year and, while an excellent vehicle for front seat comfort, entry and egress, its engine was not the most flexible and required fifth rather than sixth for motorway 50mph contra-flows. Being forced to use fifth a lot on the flat would not be good for towing a heavy caravan. You'll probably be better off with a Honda CR-V 2.2iCTDI. I see a lot of them in front of caravans. In my experience, mpg is about the same as the C-Max at about 42mpg solo average.