Whoa whoa. I bet you don't get your Hyundai all the way back. Once you turn off into Taylor Canyon your following a wash that does indeed change every time it rains (which we've been getting a lot of). I'd say you got a 32.7% chance.
When I did the Dunn Route in August, I looked down and there was bolts on the ear. Good luck.
If you're dumb and don't care about your car nor filling every bearing, joint and orifice with fine sand, then I'd say you've got a 100% chance. There really isn't anything a low clearance vehicle can't get past with enough speed.
You want a high clearance rig. It's a long way out there it would suck to get close and either have to walk in or turn around. As mentioned the "road" follows a wash. Changes all the time. Climbed it in May of 2012 and all the bolts were there. Friends did it in October 2012 and the bolts were on the ear pitch then too.
A couple friends of mine climbed Primrose Dihedrals last weekend. Bolts were in-situ and looking good. They drove their Subaru Outback in there and said it was a piece of cake with the high clearance. They had to drive slow in a couple of spots but made it sound like the road was in really good shape. Don't know how a Hyundai sedan would do though...
Well, Kor, Ingalls, and Komito drove Steve's brand new Ford Falcon in on the White Rim to do the FA on Standing Rock in '62! Hyundai, good car for tower climber, go get 'er! If not, meet me in the creek this weekend bro!