Diesel Continues To Deliver Strong Total Cost of Ownership for Many Fleets
Diesel fueling infrastructure is widely available, technicians are familiar with the technology, and vehicles can operate across a broad range of routes without relying on charging or specialized alternative-fuel infrastructure. At the same time, the growing availability of renewable diesel is giving fleets a lower-carbon fuel option, while new data and artificial intelligence (AI) tools are helping improve equipment utilization, reduce fuel consumption and extend vehicle life.
Diesel Efficiency Continues To Evolve
Fuel remains one of the largest operating expenses for most fleets, making efficiency a critical component of TCO. In the 2026 State of Sustainable Fleets Market Brief, one-third of fleet managers surveyed said they currently use fuel-efficiency technologies and nearly half plan to expand their use over the next two years.
Engine manufacturers continue to improve combustion, aerodynamics, powertrain integration and engine controls. In 2025, some on-highway Class 8 tractors achieved 10 to 11 miles per gallon while carrying heavy loads. Two tractors participating in the North American Council for Freight Efficiency’s Run on Less – Messy Middle demonstration averaged 11.6 MPG over 22,550 miles, which is a significant increase from the industry average of 6.5 MPG in 2008.
The Market Brief also reported that Volvo’s VNL achieved a 3% fuel-economy improvement through engine-component changes alone, with aerodynamic enhancements increasing the total improvement to 10%. Aftermarket technologies are contributing as well. ConMet’s TruckWings drag-reduction system, for example, has surpassed 1.5 billion real-world miles across fleet deployments.
Technology is only part of the equation. Driver behavior remains one of the largest influences on fuel efficiency and can account for 20% or more of overall performance. Effective maintenance programs can deliver additional fuel savings of 5% to 10%.
Renewable Diesel Provides Another Option
Improving sustainability does not necessarily require replacing existing diesel equipment. The use of renewable diesel (RD) and biodiesel (BD) continues to grow, giving fleets additional ways to reduce lifecycle greenhouse gas emissions.
According to the Market Brief, 56% of fleets reported using renewable diesel or biodiesel in 2025, up from 27% in 2023. Lifecycle carbon-intensity data indicated that renewable diesel reduced greenhouse gas emissions by 57% compared with conventional diesel, while biodiesel delivered a 63% reduction.
Renewable diesel can be particularly attractive for fleets that want to lower emissions while continuing to operate conventional diesel trucks. Unlike biodiesel blends, renewable diesel is chemically similar to petroleum diesel and can generally be used in existing diesel engines without vehicle modifications or changes to fueling infrastructure.
Data Is Becoming Part of the TCO Equation
Technology is also changing how fleets manage diesel equipment. Today’s vehicles generate vast amounts of data that can help fleets identify opportunities to reduce fuel use, improve utilization and optimize maintenance schedules.
AI is making those insights more actionable. Penske’s Catalyst AI™ uses artificial intelligence and machine learning to analyze fleet data and help customers improve vehicle utilization, reduce idling, identify maintenance trends and make more informed replacement decisions.
About half of the fleets surveyed for the Market Brief reported that they already use AI, primarily for route planning, maintenance diagnostics and preventive maintenance. Respondents said the technology has helped improve uptime, increase utilization and reduce costs.
Spec'ing Equipment for the Application
Choosing the right vehicle specification remains one of the most important factors affecting TCO. An engine, transmission or axle ratio that performs well in one application may increase fuel consumption, maintenance requirements or operating costs in another.
Penske works with customers to evaluate real-world operating conditions, including geography, route length, stop frequency, payload and average speed. Matching vehicle specifications to a fleet’s duty cycle can improve fuel economy, reduce maintenance costs and maximize productivity throughout the vehicle’s service life.
Looking Beyond the Purchase Price
Diesel technology continues to evolve, and external factors, including diesel prices, the price of alternative power trains, and the importance of diversification all factor into the ideal solutions for fleets.
Penske can help customers assess their operating requirements, compare available options and identify solutions that deliver the greatest value throughout the vehicle’s lifecycle while helping fleets meet their operational and sustainability goals. Contact us to learn more.