not sure what you are asking but if you stay with in the GVRW of a vehicle then you can tow or carry on roof rack. just remember everything you add including the driver is included in the max gvrw rating. it adds up fast , tool boxes , anything you put in the van.
PS Mercedes do not/did not have tow capacity rating but they are used for towing! just saying....
City Express 2014/15 SV
Dark Blue, all accessories
Tow bar. Nissan mud flaps, side protectors & all weather floor mats
(Chev does not have as option, Duh!)