It seems like pressure washers come in 3 flavours, cheap (dont waste your money on these), medium and expensive.
I have a medium black and decker that i have been very happy with, but the more you spend, the higher the pressure and cleaning the drive becomes better and quicker.
I know several people who have Karchers and have been very happy with them, but i bought the black and de ker because at the time, it had more pressure and was cheaper than the Karcher.
Nothing cleans alloy wheels better than a pressure washer.
Mine has a spinning brush for washing the car which is good, but the brush for cleaning the driveway is useless.