I have used the VX5000 Steamer for a few years now and am glad to have invested in it.
It has cut my cleaning chemical usage by probably 80%, and the distilled water I use in it only costs .99/gallon. A gallon on distilled water will easily clean an entire vehicle, including headliner, and all 4 door jambs.
It takes a little experimentation to learn how to use it effectively, and I see there are videos out there that show one how to use it more efficiently.
My particular unit is small, on wheels, and with a couple of hard styrofoam pieces underneath it, it sits just right in the top of a standard detailing cart and the hose is long enough so that you can do any part of the vehicle pretty easy.
Having it in the detailing cart allows you to also carry the towels, brushes, etc., you need to finish the job and not have to go get something else.
There are much bigger machines that are the size of probably some vacuums out there that do more than just supply steam, but I dont need anything like that, since I already have a Mytee HP60 Spyder carpet extractor.
Steam has really helped me to clean leather more effectively, it is amazing what comes out of leather once it is heated up with steam!
I read that steam has a certain amount of sanitizing ability due to the heat, and this also helps make smelly cars smell better.
I just used this steamer to clean out the oven and microwave and it did an incredible job.
This particular model comes with a whole lot of different sized types of brushes, 2 extension poles, and a window washer/squeege attachment, and a video from the man that sells the unit. All those extra brushes, cost extra if you are buying from other sellers of different steamers I believe.
This steamer is made in Italy, which I read, makes the best steamers out there.
Good luck with your research !
Dan F