At a special "Earth Day" event held in Austin, TX, Mack Trucks showed off what it's calling the "evolution" of its integrated powertrain package, based around retooled 2017 MP series engines to boost fuel efficiency and power while reducing greenhouse gas (GHG) emissions. Thanks to several new technologies and other enhancements, Mack said its new engines will boost fuel efficiency from 2.1% to 8.8% compared to its previous MP engine models.