Hybrid Semi Truck technology rolled into town a short time ago, led by a collaboration between Peterbilt and Eaton.  Already having achieved success in partnering to develop hybrid electric Class 6-7 vehicle platforms and Class 8 hybrid vehicles, the two companies are now planning to begin offering heavy-duty hybrid semis by 2009.  Concept and final design refinements of the hybrid tractor trailers is being supported by Walmart, which operates the second largest private trucking fleet in the United States. Over the next few years, Wal-Mart plans to use hybrid big rigs to increase the efficiency of their fleet by 25%. Based on independent testing, the fuel savings with hybrid semi trucks would be around $10,000 per year, when compared to similar, non-hybrid models. Those statistics don't even begin to measure the positive impact semi truck hybrids would have on the environment due to reduced emissions. Multiply this by the current semi population. Not to be outdone, Kenworth introduced a medium-duty hybrid truck at the 2007 Mid-America Trucking Show.  A Class 6 hybrid - electric semi truck, the T270 will see limited availability this year, with full scale production expected in 2008.  Industry experts agree that a hybrid tractor trailer could achieve a fuel savings of 5-10% during long hauls.  In regional delivery operations, where increased braking and reduced speeds would be the norm, efficiencies would be far greater.  Hybrid Semi Trucks are here, more are coming, and someday we'll look back and remember when far less efficient semis roamed the earth. Keep in mind that only a few years ago, hybrid car technology was in its infant stages. Look where it is today.  Only the company that will own the hybrid truck and semi market remains to be seen. View the most recent video of a hybrid Semi being developed by Walmart. The WAVE, or Walmart Advanced Vehicle Experience is a one of a kind prototype that could soon change fuel efficiency in large trucks. The Obama administration is now pushing for manufacturers to improve these types of vehicles over the next few years.