we missed the I5 turn off at the bottom of the grape vine and ended up coming back up on 99. by the time we realized it (by noticing more signs of civilization than we remembered coming down), it was too late to turn around. looking at a map, it didn't seem that we were too terribly off course. we came up 99 and cut over to 580 on 132. would anyone happen to know how much time and distance this added to our return leg? just curious. thanks.