Not surprising they say that in the manual. If you have a pressure washer, stick your hand in the jet (you'll only do it once!!
) to feel how powerful these things are. Likely to force water past any seal if you use it too close to the car.
Then again, they tell you to take care using a pressure washer but the dealers still let their 16 year old trainee loose with his grit filled sponge, bucket of dirty water and 100 year old chamois on your pride and joy when it's in for a service. Then they proudly tell you that they've washed the car for you!!
Always tell them not to wash my car and leave a large notice taped to the dashboard "DO NOT WASH THIS CAR"
Took me ages to remove all the scratches and swirls form my paintwork the first, and last, time they washed the car for me.
Same goes with all these hand car washes that have sprung up recently. Most of them use aqua blades to wipe the water off the bodywork after it's been washed with "The Gritty Sponge of Doom". One piece or grit caught in those blades and it gets dragged all the way down the panel!! DIY is best everytime for me