Tacoma Rail tested a demonstrator unit for two weeks. The technology that makes these locomotives unique is its use of multiple engine GenSets. The locomotive used by Tacoma Rail had three GenSets, each having 670 hp, for a total of 2,010 hp. The locomotive varies the use of the GenSets according to what "notch" it is in.  This is the amount of requested power from the engineer.  The on board computer automatically starts and stops the engines on demand and, when in operation, uses them in the most efficient way possible.  Depending on the duty cycles, a 25% to 60% fuel savings can be reallized.

Some statistics from RailPower:

• 25 – 60% fuel savings depending on duty cycle
• 70 – 90% reduction in NOx & diesel particulates
• 25 – 60% reduction of greenhouse gasses
• 70 – 90% noise reduction
• Lower Life Cycle Cost
• Higher availability

Further information can be found at RailPower.