A screwdriver, air compressor, and a tooth brush.
I hate using anything water based to clean my car. I try to avoid it at all costs. I dont want stuff to rust on me.
I dont like using wd-40 either as it will eat the grease in the bearings just the same but at least it wont rust things so when its just too much to handle without some sort of liquid to soften it all up I will use it. Do not allow that stuff to get on or into your engine because it will cause the seals to swell.
Money spent on a good compressor and high pressure nozzle is money well spent. I have a Porter Cable 150psi pancake compressor and a Snap-on unregulated nozzle. Most nozzles are regulated to 30-50psi The unregulated ones really do a much better job.