Lightning Hybrids has developed hydraulic hybrid systems for medium-duty trucks and buses since 2008. Their current 4th generation system is entering nationwide production and is sold through OEMs and dealers. It provides up to 40% improved fuel economy through regenerative braking. Testing shows reductions in emissions and fuel costs, with payback in 1 to 4 years. Their plug-in hybrid version combines the benefits of electrics and hydraulics. Fleets report driver acceptance and significant fuel savings after installing Lightning Hybrids systems in their medium-duty work vehicles.