Environment: Rev limiters lift fleets' fuel economy

Factory-fitted limiters cannot be removed or swapped, which can have an effect on the van’s resale value. Many fleets have limiters as standard, but not all buyers want rev or speed restrictions.

This is where a transferable rev limiting unit can offer a van operator the best of both worlds. It also allows the owner to fulfil their duty of care to the driver by ensuring the vehicle cannot exceed the national speed limit or legal maximum for that vehicle.

Most speed limiters work by taking a signal from the speedometer, measuring its frequency and then preventing the signal from going beyond this frequency.

A rev limiter works in a similar fashion, but it intercepts the signal from the throttle pedal to the rev counter and then passes it on to the engine’s ECU (electronic control unit) to restrict engine revs to a pre-set maximum.

It does not interfere with the original maker’s ECU or electronics, so there is no issue with the vehicle’s warranty.

Autokontrol’s Gerry Leggat said: “As it only adjusts the information sent to the ECU, many vehicle makers and their service departments regard a limiter as extra protection for the vehicle.”

Some insurers might be wary of an aftermarket device being fitted, but Leggat says that most insurance companies quickly come round to the idea when they see the reduced number of claims.

A spokesman for the Association of British Insurers said: “Any rev limiter that is fully approved and properly installed should not attract an increased premium as the insurance industry recognises the likely improved safety.”

There is also no room for the driver to switch off the limiter or tamper with it, as the rev-limiter is fixed behind the dash of the vehicle.

When considering whether a speed- or rev-limiter is best suited to your needs, the type of use is the major deciding factor. If your van spends a large amount of time on the motorway, a speed limiter is possibly the best solution as it offers a pre-set maximum speed.