Only time ive seen newer transits rust is when tradies havnt had the site damage repaired.
We ran a p reg smiley to 120k over 12 years and it was rusty only on the back door where a bad repair had been done and on the piller that got stoved in in the same incident
Our last transit was 5 years old when we got rid, no rust damage. 180k on the clock- my dad is fastidious about keeping his vehicles clean though- once every two weeks they get. A hand wash
In the process of repairing a sill on a mates transit its 15 years old with 180k on the clock and the sill has only just holed through! Above the cab could do with a good rub and spray mind you but its not as bad as folks make out. Ive seen my share of rusty transporters as well – t4s. How ever lets use the 00 merc vans as a base line for badly rusty vans 🙂