[Ginola]

I use a bit of Autoglym machine cleaner. I normally cover only the air intake and any exposed electrics (the rest gets very wet anyway when driving in heavy rain) spray on and use a brush, a soft one or a small wheel brush to get down in the tight to reach places.
When rinsing make sure you don't blast anything with a pressure washer close up, you just need to use your noodle and rinse it from a distance.
Its an easy job really.
You can dry up with an old microfiber, dress pipes and black bits with some vinyl care product if you wish but its not necessary.