Those findings come from NACFE’s 2025 Run on Less – Messy Middle demonstration, a three-week program that tracked 14 Class 8 trucks across 13 fleets using diesel and renewable diesel, natural gas and renewable natural gas, battery-electric, and hydrogen fuel-cell-electric powertrains. UPS participated in Run on Less – Messy Middle with a Kenworth T680 day cab powered by a Cummins X15N natural gas engine. Natural gas trucks demonstrated diesel-like range, torque and fast refueling, while newer battery-electric trucks showed improved range, weight and cost competitiveness in certain duty cycles. The organization also noted that while renewable diesel and renewable natural gas supplies are growing, production volumes remain well below what would be required for widespread fleet adoption. The organization also plans to publish four additional reports in 2026 covering operations, emissions footprints, total cost of ownership implications, and final findings that may refine the initial conclusions from the Messy Middle demonstration.