If you don't want to use a hose, then might I suggest getting the car as high in the air as you can, maybe on axle stands, and using a coupe of spray bottles? I use a pump sprayer loaded with MPC (Multi-purpose cleaner, I use Bilt-Hamber Surfex HD) and rinse off with plain water in a pump-action sprayer. A pan scrubbing brush is handy for agitating the MPC before rinsing off.
I do it with the car in the garage up on the scissor lift, using a greenhouse plant tray to catch the drips.
