IIRC, someone did an extensive post with angles & clearance calculated. See if you can find it with search. But the TLDR was that it wasn't an issue. It seems low, but because the Volt's rear bumper is not very far from the rear wheels, it's just not sticking out far when going over slopes. Compare Volt to like a Crown Vic (huge/long trunk)... it's that length that ends up being the issue.