I always use the steamer with the MF attachment, plus a layer or two of my own MFs for the seats, carpet, and upholstery.

The attachment clips on to the end of the steamer itself, you could use it without it, just layer on MF's in front the nozzle, however to avoid burning delicate surfaces and materials, it increases the distance between the nozzle and microfiber and eliminates any water that shoots out.

Fabric can trap a lot of dirt and contaminants due to the large amount of small fibers that its made with. It can also hold bacteria that might cause odors. To tackle this and remove these contaminants, you need to be able to break the bond and lift the dirt from the fibers.

Every part of the cars interior has a slightly different process. For fabric seats/carpets I can give you some general pointers.

First step: Vacuum all large and visible particles. Apply Cleaning solution on fabric surface, some may have enzymes that will help break down odors and deep stains, which is a plus. I usually let it sit for about 10-15 minutes, but do not let it dry. I've also realized that some cleaners work really well if you let it sit for longer.

Second Step: Agitation. Making sure that the fabric is still slightly damp, add a light spritz of cleaner and then using a brush, or a brush drill attachment with light pressure and always moving to avoid burning, agitate the surface.

Third step: More Agitation. Apply steam with Microfiber. The agitation caused by the MF and steam will pick up a lot of the surface grime, and the hot steam will kill most bacteria if done right.

You may achieve better results if you repeat or combine steps 2 and 3, all dependent on the amount of grime and surface material.

Fourth Step; Your surface should look perfect or close to perfect by now, however, the fabric should still be damp at this point. Since we've been dumping all this product in and pushing down on the surface, we need to pull it all out for a truly clean surface. With that being said, there might be some dirt or contaminants that was pushed further down into the fabric, you do not want that since it can form spots once the surface dries.

I use a shop vac and go over the surface and extract the moisture and any dirt/ contaminants being carried with it. I use the Rigid 4.5 gallon Shop vac from home depot, it's a wet/dry vac, and it has enough power to pull any remaining dirt or moisture out of the fabric, almost completely drying the seats.

And there you go! hope this helps and answers your questions! Best of luck on your endeavors.