Custody at the Key Cabinet: A Shift-Change Fuel Protocol for UK Pool Vans

A pool van is a shared asset with a private fuel account. The keys go into a cabinet, the vehicle goes out, and the fuel gauge moves. At the end of the shift, the next driver takes the same key and usually the same approximate level. No one records the difference. That is the half-tank handover: not a single theft or a dramatic misfuel, but a routine absence of custody between shifts. For UK fleets setting 2026 fuel budgets, the cost is rarely visible in one transaction. It accumulates across dozens of vans and hundreds of handovers until the fuel budget appears to have a slow puncture.

Why the gap sits outside the fuel-card report

Fuel cards are good at recording purchases, not custody. A card transaction shows litres, site, time, and vehicle or driver. It does not show what was in the tank when the van was returned, whether the next driver received the same level, or whether a fill was split across two shifts. Telematics can supply fuel-level data, but many light commercial vehicles report only a coarse gauge or an estimated range. The result is a reconciliation gap that is small enough to dismiss at each handover and large enough to matter across a fleet.

The arithmetic is straightforward. Thirty pool vans, three shift changes per week, forty-eight working weeks: 4,320 handovers a year. If each handover carries an unexplained two litres — a plausible margin on a coarse gauge — the fleet loses 8,640 litres. At £1.48 per litre, that is £12,787 before any card misuse or siphoning. The figure is an illustration, not a benchmark, but it explains why the protocol should be designed before the losses are itemised.

The handover record: three fields and a photograph

A workable protocol must be short enough to survive a wet Monday morning at a depot gate. Require three fields at key issue and key return: fuel gauge band, odometer reading, and the last four digits of the fuel card used since the previous handover. The gauge band should be defined in eighths rather than exact litres, because a visual gauge cannot support false precision. The odometer confirms the van has moved and provides a check against telematics. The card reference connects the purchase record to the vehicle, not merely to the driver.

A photograph of the instrument cluster is the simplest audit trail. It takes seconds and removes debate about whether the needle was at half or just below. Where a telematics platform already captures fuel level and odometer, the manual record can be reduced to an exception confirmation. The principle remains: the handover should produce a record that the next driver can accept or query at the point of transfer, not two weeks later in a monthly report.

Card-to-vehicle matching for shared vans

Pool fleets often issue cards to drivers because drivers are easier to administer. That choice undermines fuel custody. If a driver can use a card in any pool van, the transaction cannot be matched to the vehicle that consumed the fuel without additional evidence. A better arrangement is a vehicle-specific card with a driver PIN, or a card assigned to the pool location and a mandatory vehicle registration entry at the pump. Neither is expensive; both make the card report usable.

The weekly exception review should look for four patterns: a transaction outside the recorded shift window; a fuel grade inconsistent with the vehicle; a volume that exceeds the tank capacity or the plausible range since the last fill; and multiple fills on the same vehicle within a short period. These are not proof of wrongdoing. They are prompts to check the handover record before the ledger closes.

Repeat shortfalls, not single variances

A single low reading is not a case. Gauges vary, vans park on slopes, and a driver may have returned late without refuelling. The protocol should flag repeat shortfalls: for example, three consecutive handovers on the same van showing a drop greater than the agreed band, or two such events within fourteen days. The threshold should be set high enough to avoid noise and low enough to catch a persistent leak.

Investigation should follow a fixed sequence: check the card transaction, check the telematics trace, check the key cabinet record, and then speak to the drivers. In many cases the cause is administrative — a fill recorded against the wrong van, a missed handover entry, or a gauge sender that reads low when the tank is warm. The value of the flag is that it forces the sequence before blame displaces diagnosis.

A costed example for thirty pool vans

Take a fleet of thirty pool vans at one depot, with three handovers per week and forty-eight working weeks. Assume the pre-protocol unexplained gap averages 2.5 litres per handover. That is 10,800 litres a year, or £15,984 at £1.48 per litre. Now assume the protocol recovers 60 per cent of that gap through better recording and timely exception review. The recovered fuel is worth £9,590 a year.

The operating cost is modest. A weekly exception review of thirty vans should take around two hours, or £2,288 a year at a loaded rate of £22 per hour. Training and printed gauge cards might cost £600 in the first year. If the depot already has telematics, no new hardware is required. The net benefit in this illustration is roughly £6,700 in year one, before any reduction in card misuse or siphoning. For a fleet with more handovers or a larger average gap, the case strengthens quickly.

Implementing without adding friction

A thirty-day pilot is sufficient to test the protocol. Record the baseline for two weeks without changing behaviour, then introduce the three-field handover and the repeat-shortfall flag for two weeks. Review the exception rate and the time taken at the key cabinet. If the process adds more than ninety seconds per handover, simplify it. If the exception rate is above one in ten, the gauge bands or thresholds are too tight.

The objective is not to catch drivers. It is to make the fuel account continuous from one shift to the next. A pool van that leaves with a recorded band and returns with a recorded band is a van whose fuel can be costed. The half-tank handover stops being a leak and becomes a control point.