Surprise Canyon is in the Panamints, just north of Ballarat. It's good gravel road, if sometimes a bit wash-boardy. All quite doable with a 2wd rental.
Kevin, exactly the type of information I was hoping to get with this post. I've not driven down the Panamint Valley Road since the map I've used the past few years (Trails Illustrated) shows the two main access roads to the west side of the Panamints as high clearance (to Ballarat and to Warm Sulpher Springs). Ditto for going any further south than Wildrose Campground on the Emigrant Canyon Road due to a stretch of about 2 miles listed as HC. Are all three of these drivable in a typical rental sedan?
