Train #857 is on the Inland Empire-Orange County Line. I was referring to train #751 on the 91 Line that leaves Riverside-Downtown at 7:40am and arrives at West Corona at 8:04am. Even with a 15 min delay in start time, there will be 7 hours to make the first train from San Clemente, and an additional; hour and 40 minutes to make the second train back. To me that is well worth the gas and time to NOT drive an additional 35-40 miles round trip, particularly with afternoon/evening traffic on the 91, as well as being a greener alternative - IEBA would be proud of us!
http://www.metrolinktrains.com/schedules/line/name/91/service_id/1155.html