My 2012 vito dualiner auto has an annoying vibration that starts around 65mph / 100kmh... had wheel balance checked..same; had prop shaft removed, checked and balanced (balance in spec, just 10g added). Also changed rear diff oil. Same. Has been like this since I bought the van 5k miles ago, 6months. Not really getting any worse. Needs sorting as about to do a 2000mile trip end next week and I need to be going faster than 100kmh on French autoroutes. Tonight I confirmed that vibration frequency is with roadspeed, not engine speed... did this by setting cruise at 70mph and shifting between 4th and 5th. Also by knocking into neutral and confirming no change in intensity or frequency. I checked condition of diff mount bushes- look fine to me. Any ideas what to look at next people?