I have a Karcher and unlike those above find it very useful around the house and car. Good at getting the winter road grime off, especially under-body and in wheel wells. Use it to clean the deck, driveway, siding, windows too.
Ours is on wheels, so easy to move around. It also has reels for both the power cord and high pressure water line, so keeps everything nice and neat. A couple of different heads as well. All for $100 at a liquidation place 8-10 years ago.
Do need to be careful using it so as not to damage any finishes, like paint
. On siding, need to make sure you don't get under it and start lifting the siding off. On decks it will take paint right off in very narrow strips.
Tried it a couple of times for the garage floor but getting the water out, and dealing with the spray that comes up onto the walls, made that idea sort of unpractical. No floor drains so have to get the water to flow out the door(s).