<<Diesels don't have a throttle plate to create back pressure. I'm
quoting from the diesel vanagon owner's manual. Try again.>>

Neither does a Cummins, Cat, Mack, Detroit, Perkins, IH, or an other
prominent, well known oil burner.

VW
What kind of engine is that?

The engine was designed to assist in slowing the vehicle down without
totally relying upon the brakes.

The VW owner's manual isn't the last word in tactical driving
technique's & common sense.