I use one of these https://www.homebase.co.uk/ozito-1300w-1450psi-pressure-washer_p415209 on my Golf GTi. I always leave the washer 'dry' after use, by blasting it out with the water hosepipe disconnected. Usual procedure is to foam the car when it is dry. Leave for five minutes and rinse. Foam again and use those suds to wash, rinsing micro cloth in a bucket of clean warm water as I go. Rinse again. Dry with old bath towels. I don't bother hardly ever with car shampoo now, just the foam. Sometimes I use a wheel pre-clean product, but in all honesty I don't see a benefit that makes me find them value for money. If you are planning to wax, then stick some washing up liquid in the foamer bottle for the first pass as it gets shot of the old wax coating nicely. Cheap Halfords wax is pretty good, as is the polish - which I might use once a year.