Trucking is at the start of significant changes in powertrains. Fleets face evolving choices that include improved diesels, a seemingly endless variety of hybrid technologies including fuel cells, and a variety of straight electric ones including battery electric and catenary wire electric. Fuels are branded variously as “green,” “clean,” “near zero emission” and “renewable” with no clear agreement on what these mean. NACFE’s purpose in this report is to help clarify in an unbiased way the differences and similarities in this intimidating wide spectrum of developing powertrain choices facing fleets.