The hidden fuel cost of mechanical degradation
Detroit, MI, USA – June 11, 2026 — Questar Auto Technologies today announces a new white paper, The Hidden Fuel Cost of Mechanical Degradation, describing how mechanically degraded aftertreatment systems are emerging as dominant mechanical drivers of excess fuel consumption. In Questar’s analysis of one large fleet, the additional expense averages $27 per vehicle, per day.
Questar intelligence for fleet maintenance closes the loop between data and decision, moving fleet operators beyond predictive alerts to clear, actionable guidance on what is wrong, what to fix, and how.
“Fleets have long understood that mechanical degradation can increase operating costs, but until now had no way to accurately identify and quantify the cause,” says Dr. Yuval Shalev, Questar VP for Data Science and AI, and the paper’s author. “This analysis shows how advanced agentic technology can uncover hidden economic losses inside normal fleet operations and turn them into maintenance intelligence operators can take action on.”
The mixed-class fleet analyzed for the study was found to waste $25-30 in fuel every day, in every vehicle operating with degraded DPF (Diesel Particulate Filter) and SCR (Selective Catalytic Reduction) aftertreatment systems. In one cited example, a fleet vehicle shows an average of .13 – over 10% – gallons per hour wasted while idling. It is clear that even a small number of affected vehicles can create tens of thousands of dollars in avoidable annual fuel waste.
Shalev says the findings reinforce the value of proactive fleet health management. Learning how aftertreatment degradation can create major fuel waste and lead to breakdown allows fleets to prioritize service and act accordingly.
Questar customers ask the questions
Every Questar customer has real-time visibility into their fleet’s health, as well as the ability to ask questions. “Show me the quantifiable impact of aftertreatment system health on fuel consumption across my fleet’s historical data” returns a reasoned, evidence-backed analysis and recommended course of action.
How the Questar solution did it:
The question “Show me how…” initiated an autonomous research agent‘s exploration of a mixed-class commercial fleet over thousands of vehicle-days, ingesting hundreds of sensor parameters and building predictive models of fuel consumption based on operating conditions as well as vehicle manufacturer and type.
The predictive models were trained on fleet data and then used to measure the fuel gap between predicted and actual consumption, which revealed the hidden cost of mechanical condition.
The full white paper is available for download at https://questarauto.com/download-white-paper-hidden-cost-of-fuel/ .
About Questar Auto Technologies
Questar is an AI-powered fleet intelligence company revolutionizing vehicle health management for commercial fleets. Founded in 2012, Questar draws on 15+ years of telematics, diagnostics, and OEM-grade vehicle data, currently monitoring more than 350,000 commercial vehicles across four continents.
Questar is expanding across North America via its reseller partner network.