Five Quiet Fuel Leaks in Your Telematics Data — and the 30-Day Fix

Telematics platforms are usually sold on crash risk and driver behaviour. The fuel waste is less dramatic: it appears as idle hours, repeated harsh events, overlapping routes, odd fill times and slow pressure loss. These five signals are easy to export and easy to ignore. Each one has an operational fix and a place in a 30-day review.

1. Idling that looks like dwell time

Idle time is often hidden inside legitimate dwell time at depots, loading bays and customer sites. Pull the idle report by vehicle, driver and geofence, then separate engine idling from ignition-on time. A 12-van depot with 20 minutes of morning idling per van, five days a week, over 46 weeks, produces about 920 idle hours. At roughly 1.5 litres an hour, that is nearly 1,400 litres of diesel before any winter warm-up argument.

The fix is not a blanket anti-idling email. Set a five-minute threshold, review the top ten vehicles, and check whether auxiliary heaters, cab night heaters or depot power points are available. For delivery sites, ask whether engines can be switched off during paperwork. In winter, distinguish safety and defrost needs from habit.

2. Harsh braking and acceleration clusters

Harsh events per 100 miles are a fuel signal as well as a safety signal. A route with frequent hard braking is often a route with poor sequence, unrealistic schedules or repeated congestion. Compare driver scores by route, not just by driver. A good driver on a badly planned urban round can still generate high event counts.

A real-world example: a depot running multi-drop deliveries in a city centre saw harsh braking spike on the same two streets every afternoon. The issue was a delivery window that forced drivers to rush the final hour. Moving two drops to the morning and re-sequencing the route reduced both events and fuel use without changing the driver roster.

3. Route overlap and duplicate journeys

Route overlap is one of the most expensive signals because it is invisible on a fuel card statement. Map planned routes against actual geofence entries. Look for two vehicles visiting the same industrial estate, retail park or supplier within a short window. In smaller fleets, this often happens when service engineers or sales staff self-plan.

The fix is a weekly route review, not a one-off optimisation project. Consolidate supplier collections, set delivery windows by area, and give drivers a simple rule for same-day add-ons. If two vans are crossing the same postcode area, the question is whether the second journey is genuinely customer-driven or simply habit.

4. Out-of-hours fills and card mismatch

Fuel card fraud rarely looks like a stolen card. More often it is a fill outside the shift, a site far from the route, a volume above tank capacity or an odometer reading that does not move. Telematics makes these exceptions visible by matching fill time and location to vehicle movement.

Set card rules to UK fuel sites, shift windows and realistic tank volumes. Require odometer entry and review the top exceptions weekly. A single out-of-hours fill at a motorway services 40 miles from the depot is not proof of fraud, but it is a question worth asking. The operational fix is a short exception review, not a blanket ban that punishes legitimate late shifts.

5. Under-inflation and tyre drag

Under-inflation is a slow fuel leak. It also shows up in telematics as changed coasting behaviour, longer stopping distances and, on some platforms, TPMS alerts. A tyre 10% below the recommended pressure increases rolling resistance and can cost a measurable fraction of a mile per gallon across a fleet.

Build pressure checks into the weekly routine and use TPMS data where available. Calibrate gauges, check spare and trailer tyres, and record pressures by vehicle. The fuel saving is modest per tyre, but the maintenance and safety benefit is not.

The 30-day action plan

Week one: export 90 days of idle, harsh event, route and fill data. Build a one-page exception report for the top ten vehicles. Choose two signals, not five.

Week two: change one operational rule. Set idle shutdown where safe, restrict card use to site and shift windows, or consolidate two overlapping routes. Tell drivers why the rule exists.

Week three: hold short debriefs. Use vehicle-level data, not league tables. Ask drivers what makes the route difficult; the answer is often the real fix.

Week four: compare litres per 100 miles, idle hours and harsh events against the baseline. Keep the changes that moved the numbers, drop the ones that only added paperwork. Repeat the review quarterly.

Fuel waste in telematics is rarely a single dramatic leak. It is a set of small, repeatable operating habits. The fleets that control it treat the reports as a maintenance schedule, not a monthly presentation.