Rust Never Sleeps - the self-help approachviewtopic.php?p=514757#p514757
I bought the pressure washer years ago, when I still owned the Mk5. I always intended to have the wheel arches cleaned by the dealer every time it was serviced, in the hope of postponing the inevitable. They didn't do it, or did it badly. When pressure washers became cheaper, I resolved to do it myself although by then it was too late for the Mk5.
Plumbers amongst the membership will allow themselves a wry smile, but it took me quite a while to hook up the pressure washer, adding jigsaw pieces at a rate of approximately one per month.
Thread adapter, one-way valve and hose fitting (3 months):

A nice long hose (it acts as a water reservoir and buffers high pressure pulses escaping from the input to the washer) and the self-sealing Hozelock connector (2 months):

The underbody lance (another month):

At last! Ready for work (another month):

I tried it out at the weekend, and the Karcher KB 3030 (now obsolete, of course) performs well: plenty of pressure for the underbody lance, which gives a fishtail spray pattern; not too noisy; motor stops as soon as the trigger is released.
There is some sideways 'recoil' when the trigger is pressed and the spray starts because of the cranked end of the underbody lance. I need to fit a length of foam pipe insulation over the tube on the lance - wouldn't want to chip the paint on the wheel arch and cause rust spots! That will take another month ...
Phew! I need a cup of tea and a Garibaldi after that lot.

Footnote: in case you should ask, I'm still working on the letter to Ford (not enough hours in the month, etc.)