Here is a cool video I found that somebody took at the Cabin Fever show. The hill that the Mack climbs near the end is very steep. The little kid sitting in the chair on the right flipped out when he first saw the Mack and his Grandmother said " What kind of truck is that?" and the little boy said with great confidence "Thats a MACK!"
http://www.youtube.com/watch?v=a9Q7uqFmBlw