Diesel Engines Join NACFE's 'Messy Middle' as Trucking's Transition Accelerates

The North American Council for Freight Efficiency (NACFE) has placed the diesel engine inside what it calls the “messy middle” of the commercial trucking industry’s shift toward cleaner powertrains. The framing acknowledges that diesel remains deeply embedded in freight operations even as electrification and alternative fuels gain momentum.

NACFE’s “messy middle” concept describes the awkward in-between period when legacy technology and emerging solutions coexist rather than one cleanly replacing the other. Diesel engines, long the backbone of heavy-duty trucking, now sit alongside battery-electric, hydrogen and other options that are not yet ready to carry the full freight load on their own.

The takeaway for fleet operators is that diesel is not disappearing overnight. NACFE’s message points to a pragmatic transition in which diesel continues to serve many routes while zero-emission and low-carbon technologies mature, infrastructure catches up and total cost of ownership becomes clearer.