Offhand, I don't have a good recommendation.
I'm not a super excited interior detailer and for this reason, I simply don't have a great recommendation. Here's what I do know, when it comes to steam cleaners, you get what you pay for. And the more you pay, the better the ATTACHMENTS and it's the attachments that make the steam usable.
So, look at pricing but also look at the attachments.
There's also a huge difference between pressurized boiler tanks and non-pressurized boiler tanks. Not a huge deal if you're an enthusiast detailer, but if you were a professional, and doing a LOT of steam-work, you would want an unpressurized option.
The difference being, with an unpressurized steam cleaner, you can add water on-the-fly. With a pressurized version, you have to turn the unit off and let it cool own before you can add more water. For a production shop, this would be a time-killer.
What I like to do is keep it super simple. There are a few recognized brands in our industry, Meguiar's and Stoner's for example, that offer AEROSOL carpet and upholstery cleaners. This type of clean ejects a thick foam, which then sits ON TOP of the cloth surface instead of soaking into the cloth and foam underneath. This gives you some working time to scrub the cloth with the cleaner and then at some point, blot the liquids off of and out of the material.
Super old school and also super simple.
As for carpets? If we're talking about a removable floor mat - just replace them. If you really what to go nuts, purchase cheapies and then when they get dirty, simply throw them away and replace.
Some time ago, my wife drove a Mercedes-Benz SL500 with a light gray interior. After we purchased it, (with only 9000 miles on it), we took out the still-clean, perfect condition light gray Mercedes-Benz floor mats out and replace with cheapies. When we sold the car, we removed the cheapies and replaced with the factory new looking floor mats. Gave the interior a like-new look. I'd recommend this approach to anyone. Front floor mats, especially on the driver's side take a lot of abuse. Instead of trying to keep them clean and pristine, safe the new matts and replace with something you won't cry over if it becomes so soiled that it needs a hot water extractor to "try" to get them clean again.
Here's a picture of her car back when I was still at the geek. Are they even in business any longer? LOL - Management at the geek when I wored there, referred to the Show Car Garage as
wasted space. LOL
That's just my take...
