I've checked a few web sites but haven't found an answer. Also wondering if you can switch back and forth between regular unleaded fuel and E85...can they be mixed in the same tank or should it be on empty before you refill?

Contact the dealer and speak to the dealer principal. They should be able to tell you. or see this web site..
http://autorepair.about.com/b/a/220059.htm

Most manufactures put a sign or label inside the gas fuel door. Chances are a 2001 Saturn is not as it was a $250 option and most people did not have E-85 available at that time.