Downtime is the biggest hidden cost
A VOR (vehicle off road) day on a 7.5t–18t commercial vehicle averages £800–£1,200 in lost revenue plus recovery and replacement hire. On a refrigerated unit or specialist vehicle, the figure climbs to £1,500–£2,500. Preventative maintenance reduces unplanned VOR by 40–60% in fleets we have measured — typically the largest single ROI lever in any fleet. The maths is straightforward: if your fleet currently runs at 8% unplanned VOR and you bring it to 4%, on a 30-vehicle fleet that is roughly 360 vehicle-days a year reclaimed, or £290k–£430k of recovered revenue and avoided hire costs.
Parts and labour compound on neglect
A £40 brake pad swap deferred becomes a £600 disc replacement. Coolant flushes deferred become head-gasket failures at £3,500–£6,000. Operators with structured service schedules report 25–35% lower per-vehicle parts spend over the asset life, because the small jobs are done while they are still small. The compounding effect is what most reactive operators miss — it is not just that the deferred job costs more on the day; it is that the deferred job creates downstream failures that would not have happened otherwise. Run a single year of structured PM on an old fleet and the parts bill drops in year two, not year one.
Resale and insurance value the trail
Used commercial buyers and auction houses discount vehicles with patchy service history by 8–15%. On a 4-year-old 7.5t vehicle disposed at £18,000, that is £1,400–£2,700 per vehicle, per disposal cycle. Across a 30-vehicle fleet rotating every 5 years, the disposal value alone justifies a structured PM programme. Insurance is the second lever: insurers can reject claims on incidents involving vehicles with overdue maintenance, and brokers can refuse to quote after a pattern of incidents tied to maintenance gaps. The maintenance log is an asset on the balance sheet and a defence in the claims file.
Driver retention and recruitment
Drivers leave fleets with poorly maintained vehicles faster than they leave fleets with low pay. A vehicle that breaks down regularly, fails its walk-around check, or sits in the workshop with no replacement creates daily friction for the driver. Operators with structured PM report 15–20% lower driver turnover, and in a market where HGV driver recruitment costs £3k–£5k per hire, that is a material saving that rarely appears in the PM business case.
Compliance is the floor, not the ceiling
DVSA's OCRS (Operator Compliance Risk Score) factors maintenance defects directly. Operators in the red band face higher inspection frequency, public-inquiry exposure and reputational risk. Structured PM does not just reduce defects; it reduces the kind of defect that DVSA scores most heavily (safety-critical, repeat, and pattern-of-failure). The OCRS score is a leading indicator of regulatory exposure, and it improves measurably within two service cycles of a structured PM programme.
Building the business case
The PM business case sums to roughly: avoided downtime (largest), reduced parts cost (compounding), higher disposal value (predictable), lower driver turnover (often missed), and lower regulatory exposure (long-tail). On a typical 30-vehicle fleet, moving from reactive to structured PM costs £40k–£70k a year in additional planned work and returns £180k–£320k in the first year, climbing in years two and three as the compounding effects work through. The payback period is almost always inside one quarter.
Move money from the reactive line to the preventative line. The fleet pays you back inside the first quarter, and keeps paying back across every disposal cycle, every renewal, and every audit.