Last fall my husband went to rent a powerwasher to rid our siding of mold, but came back the proud owner of the Honda Excell 2600. He thought it would be a good investment, and although I was skeptical at first, now I agree.
We use this powerwasher a lot. Last weekend my husband washed his tractor, all our lawnchairs, and our kids' wading pool that had been sitting out all winter. There is a hose that you can put into a container full of detergent and it will spray soap out. After letting it sit for a few minutes, simply remove the hose from the detergent container and clean water will rinse off whatever you're washing. No scrubbing is necessary, which is a big bonus for me.
For the people out there who want the details, this unit has a 5 HP engine and sprays 2.5 gallons per minute which produces a 2600 psi stream. All that to say, it has a very powerful stream and can knock the grime off of anything.
This unit comes with about 100 feet of hose, and a wand that has three possible spray angles. It is gas-powered (which makes it very portable) and a bit loud.
If you are in the market for a powerwasher, this unit made by Honda is a good bet for the price.