I wash 2 cars most weekends so am always looking ways of speeding it up, while still doing a good job. This section of the website is great for finding ways of slowing me down.
I spray the lower half of the car with Traffic Film Remover in a garden sprayer. While the car soaks, I set up the pressure washer and fill a bucket (+ grit guard) with car shampoo.
Pressure wash car. Put pressure washer away and attach garden hose gun, set to wide spay. I find this more effective for rinsing the shampoo off the car.
Using a white Megs microfiber mitt - start at the top of the car and wash down. Do the lower panels 1 at a time. Check the mitt for dirt. Reverse the mitt and use the clean side when necessary. When both sides of the mitt are dirty, put it against the outside of the bucket and use the garden hose gun to clean it. Ring out the water. I find this more effective than the 2 bucket method.
Leave the lowest 3 inches around the whole car to the very last. It is the dirtiest part and you don't want to be rubbing a dirty mitt over any of the panels.
Use wheel mitt to wash the wheels.
That takes me 40 minutes per car. I don't think I could do it properly any faster.
The key to good results is drying the car. (This may be controversial.) If I'm in a hurry I will use a rubber blade to squeegee the cars. (I may have to spend some time in the naughty corner for that
) Though I much prefer to use about 12 sprays of aqua wax over the wet car. Then a microfiber towel to remove the water and a dry microfiber towel to buff the car. This does take a longer, but gives much better results.
When my Aqua Wax runs out I going to try some Gtechniq c2v3 as a drying aid.