Get a power washer. Ours was about $220 at Costco a few years ago, and we use it several times every year, including for washing cars.

I have a little Black/Decker electric power washer that I use for smaller jobs - patio, patio furniture, planters, low setting for my cedar decking. I think it was about $100-110 at Home Depot.

For larger jobs like the circular driveway, moss on the walk and driveway at an elderly friend who he helps, DH borrows our BILs bigger gas model for faster results.

But I wouldn't use either on our waxed car or truck...those are done by hand most every week. Every week with the truck which is off highway, at least every other with my car ;)

I'm not a fan of power washers. I've tried a few times to use them, and they take off light surface dust. But in my opinion, they don't do well in removing dirt and grime, and in the hands of non-experts, a power washer can do a lot of damage.

I think that the friction of a cloth or sponge or an electric scrubber - which is what I think you are asking about - is far better than a power washer. Unfortunately, I have not found a power scrubber for outdoor use. There are some that run on batteries, but I think you need something more powerful and longer lasting.

There are brushes you can put on the end of your drill. I have never used one.

Here is a link that might be useful: drill brush

I solved my deck furniture cleaning, I just took it to The Gently Used Store. LOL I realized I just made another room that had to be cleaned.

Thank you everyone. I totally agree with you graywings. I don't like to use power washer. It can do a lot of damage as you said.

that one with drill brushes is a great idea i have never used it. I will try it this weekend.