Is alcohol the best thing to clean sofa and carseat fabric?
Make a sudsy mix of detergent and water and just use the suds to clean.
Are you trying to remove a stain or just standard cleaning.
We use Resolve brand upholstery cleaner for periodically freshening up of car and couch upholstery. Test it in an inconspicuous spot first. We had tried another brand and it stained the couch. Water and dish soap stained my gray car upholstery. Trial and error got us to the Resolve brand. I am very anti chemical, so we only use this rarely. Use this in a well ventilated space. For the car try to do it on a dry, cloudy day so the heat doesn't bake the smell in.