I had a friend who was a mechanic in the Montgomery County Md school bus yard. These things use a heavy duty truck chassis and then add more metal. You do not want to get hit by one, even in an H1 Hummer. These things weigh from 12-18 tons empty, depending on what size it is. Some places have to use smaller busses just because of the bridges they have to cross. Yeah the vehicle to load weight ratio is ridiculous and they get 6-7 MPG (Diesel). Our district logs a couple million miles a year. There are also lots of rules for the drivers. In Lee County they need an extra validation their license to back up. We got that from the director of transportation when we asked why all the school busses were lapping our neighborhood and never dropped off any kids. They were not allowed to turn around if it required backing up. We are at the end of a dead end road so they just "went around the block", a one mile trip according to the joggers.