Hi Cheryl,
I valet alot of vehicles and you find as 'Doug' sugests HWE can be used safely on most vehicle upholstery. Use a fabric solution but try not to use any solution with brighteners in it. Hold your hand tool about 12 inches away from the material and spray, lightly srub then extract. Dont over wet at this time of year and if you have got one, a plastic seat cover is advisable when you've finished and ask the customer to take off the cover at night to allow it to dry faster Advise your customer that it could take two days at this time of year for the seat to dry properly so keep hold of the cover until dry. hope this helps need further advice pm me