Fabric can usually be cleaned with soapy water or a proper detergent. For more difficult spots caused by oil, ice cream, soda, etc., use a fabric cleaner available at most parts stores. Be sure when purchasing the cleaner to read the label to ensure it is safe to use on your type of fabric. A safe method of testing the cleaner is to apply a small amount to an area usually unseen, such as under a seat, or other areas. Wait a while, perhaps even a day to check the spot for fading, discoloring, etc., as some cleaners will only cause these problems after they have dried.
Leather upholstery requires special care, it can be cleaned with a mild soap and a soft cloth. It is recommended that a special leather cleaner be used to clean but also treat the leather surfaces in your vehicle. Leather surfaces can age quickly and can crack if not properly taken care of, so it is vital that the leather surfaces be maintained.