Lightman, I'm not sure of a spec for this. However, here are some ways you can deduce or find out. the black hose is 7.5 mm, so the clear hose MAY be the same. Or, you can order one of clear hoses from the dealer and have it measured. I know you did not ask this, but if you are mounting anything to the frame, I would use the black hose as I believe its a lot more flexible. Note that even your VW has SOME flexible hose before going to the more rigid clear hose.

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Brian Toscano