Where the Data Comes From

The device determines what you can see, and the differences are larger than the price differences suggest.

The diagnostic port

A dongle in the OBD socket, which every light vehicle has.

Reads: standard diagnostic codes, engine speed, coolant temperature, fuel level, odometer on many vehicles.

Installed in seconds and removed in seconds, which is convenient and is also how it gets unplugged.

Limitation: the standard set is narrow. Manufacturer-specific data is frequently not exposed, so the fault code you get may be generic where the vehicle knows something more precise.

Direct CAN bus connection

Wired into the vehicle network, usually by an installer.

Reads far more: manufacturer-specific codes, fuel consumption calculated by the engine rather than estimated, adblue level, seatbelt and door status, tyre pressure on vehicles that report it.

Costs an installation and is vehicle-specific.

This is where the maintenance and fuel value actually lives, and a fleet that buys dongles to save on installation frequently discovers it a year later.

Manufacturer telematics

Built in by the vehicle maker, delivered through their platform or an API.

Reads whatever they choose to expose, which is improving and varies enormously by brand and model year.

No installation, no hardware, and no consistency across a mixed fleet.

Ask what the API provides before assuming it removes the need for devices — frequently it provides position and little else.

Tachograph and regulated devices

In heavy goods vehicles, already present and already recording driving time, breaks and rest under a separate legal regime.

Which answers the driver hours question without any telematics purchase, and has its own rules on access and retention.

Ask what the tachograph already gives you before specifying anything, because in regulated transport a substantial share of the questions are covered.

Choosing

Start from the questions you want answered, not the price per device.

Position only: a dongle is adequate.

Fuel, maintenance and condition: CAN connection, or manufacturer data where it genuinely covers it.

Mixed fleet: expect a mixed answer, and plan for the reporting to normalise across sources rather than assuming one device everywhere.

Ask for the field list per model

The question that separates a specification from a measurement.

Not "does it read engine data" but which parameters, on which vehicle model, from which connection.

A vendor answering identically for every model is describing the product rather than your fleet.

Get it in writing before purchase, and verify the first vehicle of each model against its dashboard at fitting.

A practical configuration prompt

During configuration, use employee productivity reporting for field teams to prompt questions about identifiers, ownership and output. Treat the page as a starting point and document each assumption.