the accident that caused that much significant damage to the vehicle clearly indicates he was well out of the "speed limit" if he was doing under 70mph i'd be surprised to be honest. to tear a wheel away from the car, cause the ripple in the back end of the escalade as well as pop out the windows... yeah speed was 100% a factor.
also. take into account the initial point of impact, and how far the vehicle traveled to its final resting spot. that's quite a bit of distance from where the hydrant is.