 The Model 40, first delivered in 2003, is a two-foot (24.5 inches) shorter variant of the Model 45, with less passenger room, but otherwise comparable characteristics and performance data.The model 40 also lacked an APU or Auxiliary Power Unit.The Model 40XR, introduced in 2004, is a higher-performance variant of the Model 40, with the same modifications as used to convert the Model 45 into the Model 45XR.