When it comes to automotive carpet cleaning, steam cleaning is not the best fit. For residential carpet cleaning, there is nothing better. It removes the most soil and is safest for carpet. This is why major carpet manufacturers recommend this method. Auto carpet is a different animal however. It is harder to dry and because most of it is Olefin, the water tends to run down the fiber and to the backing of the carpet. And, what is behind that carpet backing? Hard to dry insulation and electrical wiring, not to mention sheet metal that could rust.
The best method to clean auto upholstery may not be the most effective but it is safe. We like foam cleaning for auto upholstery. You may have to repeat the cleaning several times to remove all of the soil in your vehicle but it is unlikely to over-wet your carpet.
The cleaning process with foam is very easy. You simply spray it on the carpet and agitate it with a brush. You can then either wait for it to dry and vacuum it up or you can wipe it with a towel to remove heavier amounts of soil.
If you want to give foam cleaning a try on your vehicle, you can find cans of the cleaner like the one pictured above at most auto repair stores.