Hi John
Had my C-max 2.0 TDCI Ghia for over 12 months now and tow a Swift Charisma 535 @ 1291 Kg if fully loaded, this gives an 85% van to kerbweight ratio exactly. Two trips to Cornwall / Devon plus several other shorter runs. No probs towing and car cruises comfortably in 6th gear on motorways. Obviously I have to use lower gears on inclins but car does not struggle. 30 to 34 mpg when towing.
Hope this helps but if you have any other questions please ask.
Alan