STIHL RE270K HIGH-PRESSURE WASHER is what I use, very powerful...bit too powerful to be hones!
So much so I deliberately removed all the paint work from my mountain bike using it, saved me hours instead of sanding! I always use the foam attachment and spray from a distance to avoid jetting water in places it shouldn't be, like the headlamps.
I think handwashing is the best way to clean a car, pressure washers are a bit crude, they just spread the dirt about rather than totally remove it.
they are good for tyres wheel arches and underneath the car/ rinsing, but for a real clean finish, get your bucket and sponge out!