Documentation

Fuel Report

The Fuel Report shows fuel fillings, drains, and consumption for your vehicles over a selected time period. It automatically detects refueling events and unexpected drains from the vehicle's fuel level sensor, then breaks down fuel balance and consumption by vehicle and by day.

This report only works for vehicles with a fuel level sensor and calibration configured (see the Sensors documentation). Vehicles without one still appear in the report, but only with raw mileage/engine-hour data — any missing fuel data is explained in the Note tab.

Generating a Report

1. Select Vehicles: Choose one or more vehicles from the dropdown
2. Select Groups (Optional): Choose vehicle groups to include all vehicles in those groups
3. Set Date Range: Select a predefined range or set custom dates
4. Click Show to generate the report
5. Click the export icon to download the full report as an Excel file

The report is organized into five tabs: Fills and drains, Summary, Detailed, Parameters, and Note.

Fills and Drains Tab

This tab lists every individual fuel filling and drain event detected for the selected vehicles, with:

• Date and Period — when the event started and finished
• Sensor type — the fuel sensor used
• Balance at start / Balance at end — fuel level (in liters) right before and right after the event
• Fill / Drain — the amount added or lost
• Location — the nearest GPS position to the event, reverse-geocoded into an address

Click any row to open a chart for that vehicle, automatically zoomed in around that specific event (with 30 minutes of context on each side) so you can see exactly what the fuel sensor was doing. Click the same row again, or the ✕ button on the chart, to close it. Click a different row to switch the chart to a different event or vehicle.

While the chart is open:

• The faint blue line is the raw sensor reading; the bold blue line is the median-filtered level used for detection
• Green/yellow/orange shaded backgrounds show the vehicle's motion state (moving, stopped, parked, no signal)
• Green/red arrow markers point to detected fills/drains — click a marker for a popup with the exact before/after levels and volume
• Use Reset zoom to return to the full event window without closing the chart

How Fills and Drains Are Detected

Detection follows the same algorithm used by Wialon and similar fleet-tracking platforms. The process has three stages: filtering, event detection, and volume calculation.

1. Median filtering

Before any event detection, the raw sensor readings are smoothed using a centered time-based median filter. For each reading, the system collects all readings within a ±1.5-minute window around it, sorts them, and takes the median as the smoothed value.

A median filter is used instead of a simple moving average because a single corrupt or out-of-range reading (for example, a sensor glitch that reports 0 L for one second) has no effect on the median — it gets sorted to the edge and discarded. A moving average would pull the entire smoothed line toward that outlier.

The filter window width can be adjusted per sensor in the sensor settings.

2. Event detection

The system scans the smoothed fuel level message by message, looking for a sustained rise (filling) or fall (drain):

• Start of a run: recorded at the last stable reading before the first rising or falling step — this is the true pre-event baseline (Wialon calls this Vinit = Vprev). Using the reading just before the first delta, rather than the first delta itself, ensures the full event magnitude is captured.
• Run extension: the run continues as long as the level keeps moving in the same direction. A single small step backward (sensor settling noise) does not end the run — only a reversal larger than half the minimum threshold closes it.
• Stops-only filtering: fills and drains can each independently be restricted to periods when the vehicle is not moving. A fill detected during driving is almost always a sensor noise spike from vehicle vibration, not a real refueling. A drain detected during driving is normal fuel consumption, not theft. The Fill stops only and Drain stops only settings (configurable per sensor) control this.
• Events below the minimum volume threshold are discarded as noise. The thresholds are listed in the Parameters tab.

3. Volume calculation (raw boundary override)

The median filter smears the boundary of a fast event: at the start timestamp, the right half of the filter window already contains readings from during the fill, pulling the smoothed value slightly higher than the true pre-fill baseline. At the end timestamp, the left half still contains pre-fill readings, pulling the smoothed value slightly lower than the true post-fill level.

To correct for this, the system applies Wialon's raw boundary override: it checks the unfiltered (raw) sensor value at the exact start and end timestamps. For a fill, if the raw value at the start is lower than the smoothed value, the raw value is used as the true baseline (it wasn't affected by the filter smearing). If the raw value at the end is higher than the smoothed value, the raw value is used as the true post-fill level. The same logic applies in reverse for drains. The raw override is capped at twice the filtered change to guard against a single corrupt reading at the boundary moment.

Calibration accuracy

The volume reported for each fill or drain is only as accurate as the sensor's calibration table (the raw sensor value → liters mapping). If the calibration table is inaccurate in a certain fuel level range, the reported volume will differ from the actual amount pumped, regardless of the algorithm. If fill volumes consistently differ from fuel receipts, the sensor's calibration table should be verified and rebuilt using known fuel amounts at multiple tank levels.

Summary Tab

One row per vehicle, totaling the entire selected period:

• Mileage and Motor hours — total distance and engine-on time
• Balance at start / Balance at end — fuel level at the very first and very last sensor reading in the period
• Fill / Drain — totals of all detected events
• Total consumption — fuel actually burned by the engine, calculated as: balance at start + fill − drain − balance at end
• Consumption per hour and per 100 km — the same total consumption expressed as a rate

Detailed Tab

The same metrics as Summary, but broken down per vehicle, per day. Each row's mileage and motor hours come directly from the device's own daily counters; fill/drain/balance/consumption are calculated the same way as Summary, but scoped to that single day.

Click any row to open a chart showing that vehicle's daily fuel balance trend (line) with that day's fills (green bars) and drains (red bars) overlaid — useful for spotting which day a slow leak or a series of top-ups happened. Click the same row, or the ✕ button, to close it.

A filling or drain that starts just before midnight and finishes just after is counted entirely on the day it started, not split across both days.

Parameters Tab

Documents the exact detection settings used to generate the report for each vehicle:

This tab is for transparency: if a top-up or drain doesn't appear in the report, check here to see what threshold it would have needed to clear.

These settings default to the same values for every vehicle, but can be overridden per fuel sensor (see the Sensors documentation) — useful if a particular tank or sensor is noisier, or has a different minimum meaningful fill/drain size, than the rest of your fleet.

Note Tab

Lists any selected vehicle that has no fuel sensor calibration configured, which is why it has no fill/drain/balance data in the other tabs. Configure a calibration curve for that vehicle's fuel sensor and re-run the report to include it.

Exporting

The export button downloads a single Excel file with one sheet per tab (Fills and drains, Summary, Detailed, Parameters, Note) — the same structure you see on screen, so it can be shared or archived as a complete record.

Scheduling

Use the Schedule this report control next to the export button to have this report run automatically and emailed to chosen recipients — on desktop it's a calendar-icon button, on mobile/tablet it's inside a dropdown menu. It opens the Schedules page pre-filled with the vehicles, groups, and date range currently selected. Each scheduled run emails five CSV files, one per tab. See Scheduled Reports for the full setup options (recurrence, recipients, etc.).

Use Cases

• Theft/Leak Detection: Spot unexpected drains while a vehicle is parked
• Refueling Audit: Cross-check driver-reported fuel fillings against sensor-detected ones
• Consumption Analysis: Compare consumption per 100 km across vehicles to spot inefficiency or a developing mechanical issue
• Daily Investigation: Use the Detailed tab to pinpoint exactly which day an anomaly happened

No Data Found

If a vehicle shows no fuel data:

• Check the Note tab — it likely has no fuel sensor calibration configured
• Verify the vehicle was active (reporting GPS positions) during the selected dates
• A vehicle with very stable fuel use and no fillings/drains during the period will still show Summary/Detailed totals — it just won't have any rows in the Fills and Drains tab