my old cossie ( L22 COS ) was a modified cosworth show car and i would wash the bottom half with auto glym/triplewax shampoo and usuall rinse with a different sponge.

washing the whole car usually got water all over the alloy under the bonnet and was hard to get back into all the bits on the inner wings and chassis rails.

i found after fast road or track use it had to be washed rather than wiped and polished !!!!!!!!!