Parts and Labor Costs Dipped in Q4 2025 — But the Five-Year Trend Is Still Telling a Different Story

The Quarterly Number: What Happened and Why

Combined parts and labor costs declined 1.3% from Q3 to Q4 2025. That followed a 3.8% increase in the prior quarter, so the net movement over the second half of 2025 is still a cost increase — just a smaller one than it looked like in September.

Breaking it down: parts costs fell 0.4% quarter over quarter. Labor costs fell 2.6%. Both categories moved in the right direction, which is genuinely uncommon — over the past two years, the pattern has been one or both categories rising in any given quarter. Two simultaneous declines is real improvement, even if the magnitude is modest.

The explanation for the dip is not that trucks got cheaper to fix. It is that trucks ran less. The ATA’s seasonally adjusted For-Hire Truck Tonnage Index fell 1.8% from Q3 to Q4, and came in 0.3% below the final quarter of 2024. Freight activity was suppressed by soft manufacturing and construction demand — sectors that drive a large portion of commercial vehicle utilization. When trucks run fewer miles, they generate fewer service events, and the aggregate spend on parts and labor moves accordingly. For all of 2025, ATA tonnage rose just 0.1% over the 2024 average. The industry ran nearly flat all year.

This is the critical context for interpreting the Q4 maintenance cost decline. The relief in your shop bill came because the freight market was soft, not because anything structural changed in what it costs to maintain a heavy-duty truck. If freight volumes pick back up — as every forecast in the industry suggests they will — the maintenance cost pressure comes back with it.

The Year-Over-Year Reality

Quarter-over-quarter comparisons smooth over the real trend. Year over year tells a more honest story.

Comparing Q4 2025 to Q4 2024, combined parts and labor costs rose 2%. That is still upward momentum on an annual basis. And within that 2% overall increase, the components tell you which side of the cost structure is now driving the pressure: parts costs were up 3.7% year over year, while labor costs actually fell a modest 0.4%.

That reversal in the parts-versus-labor dynamic is worth paying attention to. For the past several years, labor has been the dominant driver of maintenance cost inflation — the technician shortage pushed shop rates up consistently, and there was no near-term structural fix for that problem. The Q4 data suggests labor costs may be finding a ceiling, at least temporarily. Fewer service events mean less demand for technician time, which takes some pressure off shop labor rates.

Parts, however, are accelerating. Parts costs rose in 19 of the 25 VMRS vehicle systems tracked in the benchmark, and year over year showed increases in 16 of those systems. The shift from labor-driven to parts-driven maintenance inflation is not a technicality — it changes where you should be focusing your cost management attention and what the tariff environment means for your operation specifically.

The Six-Year Picture: What Has Actually Happened Since 2020

The quarterly fluctuations sit on top of a longer-term trend that is sobering regardless of which direction last quarter moved.

Since early 2020, combined parts and labor costs for heavy-duty truck maintenance have risen 27.4%. Parts are up 23.8% over that period. Labor is up 33.5%. To put that in operational terms: if your shop costs were running $1,000 per month per truck five years ago, the equivalent maintenance workload now runs roughly $1,274. That increase has happened while freight rates, for most of 2022 through 2025, were declining or stagnant. The cost side of your operation moved significantly higher while the revenue side compressed.

The single largest cost increase by vehicle system over that six-year window is cab and sheet metal — a category that rose 63.8% combined, with parts up 68% and labor up 58%. That is the system category that includes collision damage repair, rust, structural work, and body components — areas where raw material input costs have been the primary driver, and where tariff exposure on steel and aluminum is most direct.

The Tariff Variable: What the Data Cannot Directly Measure — But What It Shows

When asked directly whether tariffs are contributing to the rise in parts costs, Decisiv’s leadership was careful but clear. The benchmark dataset does not have a field for “tariff-driven price increase” — it records what shops charged for parts, not why those parts cost what they cost. But the timing correlation is visible in the data. Parts cost increases began accelerating around the time steel and aluminum tariffs were introduced, and the cab and sheet metal category — the one most directly exposed to raw material input costs — shows the steepest increase of any system code in the benchmark.

The broader tariff picture for trucking parts is significant. Steel and aluminum imports now face 50% Section 232 tariffs, and those materials flow directly into the manufacturing of brake components, chassis parts, body panels, frames, and structural hardware. A 25% tariff on imported heavy trucks was put in place in October 2025, and while that directly affects new truck acquisition costs — ATA estimated the tariff adds up to $35,000 to the price of an imported Class 8 — it also affects the used equipment market and the competitive dynamics of fleet replacement decisions.

What Decisiv’s CEO Tim Hardin noted goes further than just the direct cost of tariffed components. Supply chain uncertainty, he pointed out, tends to get priced in ahead of actual shortages. When distributors and parts manufacturers believe tariff-driven supply disruptions are coming, they adjust pricing preemptively. “Typically what I’ve seen is it gets priced into the supply chain regardless of whether there’s a physical impact or not,” Hardin said. For an owner-operator buying a water pump or a set of injectors, the distinction between actual tariff impact and supply chain anxiety pricing is academic — the price on the invoice is higher either way.

What This Means for ATRI’s Operational Cost Picture

The Decisiv benchmark data aligns with what the American Transportation Research Institute found in its own operational cost analysis. ATRI reported that repair and maintenance costs fell slightly from 2023 to 2024 — dropping from approximately $0.202 to $0.198 per mile — but noted that Q1 2025 already showed R&M costs rising again, up 2.8%. ATRI’s report also found that smaller fleets bear a disproportionate maintenance cost burden: fleets with five to twenty-five trucks handle only about 48% of their maintenance in-house, compared to 62% for fleets over 1,000 trucks. When you are paying shop labor rates at an independent service provider rather than running your own technicians, every dollar of the industry-wide labor rate increase hits you harder than it hits a large carrier with its own maintenance infrastructure.

The broader ATRI picture on non-fuel operating costs is the context in which the maintenance data sits. Non-fuel operating costs hit a record high in 2024 — $1.779 per mile, up 3.6% from the year before. Equipment lease and purchase payments are up 70% since 2015. Insurance premiums are rising. Driver compensation is still elevated from the post-pandemic runup. Maintenance is one component of a cost structure that has been moving uniformly higher while freight revenue has stagnated or declined.

The Technician Problem Is Not Going Away

The 33.5% increase in labor costs since 2020 is not simply post-pandemic wage inflation. It reflects a structural deficit in the diesel technician pipeline that has been building for a decade and that no single policy or market correction is going to reverse quickly.

The TMC tracks technician compensation and workforce data separately from the benchmark report, and its recent surveys confirm what every fleet manager and shop owner already knows from daily experience: qualified diesel technicians are difficult to hire, difficult to retain, and increasingly expensive at every point in the compensation curve. Entry-level technician pay has risen sharply because shops are competing for a limited pool of new graduates from diesel tech programs. Experienced technician pay has risen even faster because the senior-level workforce is aging and not being replaced at the same rate.

The Q4 dip in labor costs is probably not a trend reversal in the technician market. It is more likely a reflection of reduced service volume — when trucks run fewer miles, they need fewer service hours, and the aggregate spend on labor falls accordingly. When freight recovers and trucks start running harder, the demand for technician time will increase, and the structural supply deficit will reassert itself in shop rates.

What Small Carriers and Owner-Operators Should Do With This Data

The benchmark data from Decisiv and TMC is not just industry trivia. It is a diagnostic tool for understanding whether your own maintenance costs are tracking with the market or running above it — and it points to specific areas where cost management attention produces the most return.

Parts costs are where the battle is right now. The shift from labor-driven to parts-driven cost inflation means that your purchasing decisions on components have more leverage than they did two years ago. The difference between buying OEM parts at a dealer versus high-quality aftermarket from a reputable distributor is a real dollar impact on your cost structure, not just a theoretical debate. The same logic applies to buying parts in advance when pricing is stable versus buying reactively when you need something immediately at whatever price is on the shelf. Predictive maintenance — knowing what is going to fail before it does — gives you the purchasing window to control cost on parts that are now your primary inflation exposure.

The cab and sheet metal category is the largest cost driver over the past five years. That category includes the type of damage that often gets deferred — cosmetic rust, minor body damage, small dents that do not affect function but do affect corrosion progression. Deferring that work because the truck runs fine is a rational short-term decision that creates accelerating repair costs as corrosion spreads. In a tariff environment where steel and aluminum components cost significantly more than they did before, the economic case for addressing sheet metal issues earlier rather than later is stronger than it used to be.

The quarterly decline is a floor, not a ceiling. The 1.3% Q4 decrease came from lower freight activity, not from structural improvement in what trucks cost to maintain. When the freight market recovers — and the current consensus among economists and freight analysts is that recovery is coming in 2025 and 2026, driven by inventory restocking, nearshoring-related manufacturing investment, and a normalization of the capacity overbuild that has suppressed rates for three years — utilization goes up, service events go up, and parts and labor costs will follow. Plan your maintenance budget for the recovery scenario, not for the soft-freight scenario that produced the Q4 number.

If you are deferring maintenance because cash is tight, understand exactly what you are doing. The freight recession has put pressure on cash flow throughout the industry, and deferred maintenance is a rational short-term response to a cash constraint. But the Decisiv data makes the compounding cost dynamic visible: deferred maintenance that creates an unscheduled breakdown costs more per event than scheduled maintenance, drives higher shop rates because you are paying for emergency service versus planned service, and removes the truck from revenue-generating activity at the worst possible moment. The carriers that come out of the freight recession with their operations intact are the ones who maintained their equipment through the downturn rather than gambling on getting to the recovery without a major breakdown.

The Q4 maintenance cost dip is real, and it is not nothing. After the 3.8% increase in Q3, a reversal is directionally meaningful. But the data also tells you that you are managing a cost structure that is 27.4% more expensive than it was five years ago, that parts costs are now the primary inflation driver with tariff tailwinds behind them, and that the quarterly improvement was largely the product of a freight market that ran soft all year. The carriers who use this data as a planning tool — rather than as reassurance that the problem is receding — are the ones who will be positioned when the recovery arrives.