While traveling at highway speeds 75+ a loud bang and then control of vehicle was hard to keep on road, swerved left then right, left rear quarter panel hit guard rail and caused car to spin around and went sideways and backwards down a 30 ft embankment. Fortunately did not roll. left side tires came off of rims and damage to driver side door was done. Highway Patrol had car towed to holding lot, where I then got car towed to my mechanic. The left side Lateral stabilizer Rod had broken due to rusted part, causing left rear wheel to go out of alignment. The rubber boot on the rod was attached, rust was internal would never had known about a problem. Had both lateral rods replaced tires re-balanced and alignment done.