Indeed, looking at the Bentley engine, beside the alternator is the plate oil cooler. Apparently VW W12 doesn't have the cooler in the same location thus allowing for a shorter belt due to alternator location..

 

 

The belt can be changed without removing the front bumper and assorted radiator pieces. The procedure is not for the light of heart. because one needs to do the job from below.

A synoptic explanation follows. Remove the top brace with the assorted torx head screws, this will allow a little bit of room on top to fidget. Next lift the front of the car enough to have handy access to remove the undershield. Now with a serpentine belt tool, access the hexhead compression release on the serpentine belt tensioner. The tool will have to be used from below. Relieve the tension on the belt and remove from the air conditioner compressor pully on the left side. Make a diagram of the routing before doing anything. Now fish the new belt around all the appropriate pulleys. From above you can access some of the routing. Leave a loose loop by the air conditioner compressor. Once again using the Serpentine Belt Tool release the pressure and install the loose loop around the air conditioning compressor pulley. Sounds simple enough but it takes several tries with the serpentine belt tool to get everything right. Having a car lift makes it much easier since one will be standing instead of lying down. Having a helper would make it even easier they can run the tool while the other guy messes with the belt.

This is a quick explanation. Someone with patience and experience can do it this way. Procedure is probably not the Bentley way but doesn't require complete disassembly of the front of the motor.

 

 

Changing the belt is a royal pain in the **** I did mine recently but I had to replace my bumper.i removed the bolts supporting the radiator and bumper support .put a jack under the radiator (to take the weight) removing the bolts game me enough room to undo the tensioner and remove belt.after lots of swearing and cuts to the hands I managed to remove it.i then squeezed tensioner closed and put a very large cable tie around it for refitting(measure distance between bolt holes and adjust accordingly .then came the fun bit.i rolled around on the floor whilst my friend helped from above and we got it back together within the hour.a horrible job but it saved draining all the fluids and Aircon and removing the front .just a note I think all the vw pheaton and other engines only have a one sided belt .stupidly I never took the number from the belt but I think my friend took a picture so I'll see if Incan find the number

 

Well here we go again .the door switch on the Bentley was faulty I think water had got into it after I took it all apart .once again flying spares and scudaria wanted to rob me of my hard earned cash and I'm sure many other breakers yards would have tried too.so the search began.5 mins I found the perfect replacement .VW pheaton is exactly the same .removed circuit board swapped into Bentley housing plugged in job done £50 .I think I'm gonna open up a fairly priced Bentley spares site .with what I've found already I think I could help everyone with some fair prices .

 

I look at the belt pattern in all 3 engines, and even if the Audi and Bentley run differently through the pulley's I think you can install your belt in both ways since the pulleys will always turn in the right direction.