I use Epic Waterless Wash to wash my car every two weeks. I takes about 15 minutes, max. Cleaned, dried, waxed, protected ... 15 minutes. I use the bucket method because my car stays outside and two weeks is enough to get it pretty dirty.
We're finally taking the drought seriously. In California, people are talking about saving water in a bucket while the shower warms up to flush the toilets or water the plants. We may have to kill the lawns but there is no reason to have a dirty car. I'll probably stick with Waterless wash even after the drought.
Bob made a short video to demonstrate how fast and easy it is. Check it out.