That's super sketchy. I was trying to figure out exactly how long the ascent is, and far it is, but can't find concrete data. All I know is it's SUPER long with a 5-6% grade for a lot of the way. The only thing I can compare it to is the Castaic Grade in SLO which is 7% and climbs 1500 odd feet. At around 60 mph I lost almost 10%. Going down it on my way home I gained 2-3%, but I knew the Castaic Grade would take a lot so I charged in SLO before I continued to Paso. I would honestly be worried about taking the Grapevine and would instead go around to the 14 and stop to charge in that area.