On maps this trail is called Mason Valley Truck Trail, it's also known as Oriflamme Canyon. The trail starts out as a very easy dirt road until you reach the canyon. Once you get to the canyon the trail starts to climb up a steep and rocky narrow shelf road. This trail should really only be attempted in a Jeep or something equivalent. For a Subaru the trail will test the limits of your driving skills and car.
Trail Start: 33.00754, -116.45634
Trail End: 33.01845, -116.56140
GPX Track File: https://201d7a3b-d44f-494f-b5ce-dbc682c6740e.filesusr.com/ugd/6996ba_8aa9588a7a8b480a8345fd67fd0c783f.gpx?dn=mason-valley_oriflamme-canyon.gpx
KML Track File: https://201d7a3b-d44f-494f-b5ce-dbc682c6740e.filesusr.com/ugd/6996ba_185f7d48242040a1add4d3aa16a8ad7f.kml?dn=mason-valley_oriflamme-canyon.kml