A major utilities company has trialled the use of a rev limiter across 19 vans and found that fuel consumption dropped by 24.72%.

This remarkable result is an impressive demonstration of the benefits of optimising use of engine torque and preventing over revving.

The rev limiter was supplied by Autokontrol and was fitted to 19 vehicles ranging from mid-sized panel vans through to 3.5 tonne GVW vans and tippers as well as 4×4 pick-up trucks.  All 19 vehicles involved were running at maximum gross weight with the majority of them used to tow trailers.

This was a demanding test for any device claiming to improve fuel economy and the results were very impressive. The average fuel economy improvement across all 19 vehicles in the trial was an exceptional 4.42 mpg or 24.72% economy gain, with some of the 3.5 tonne vehicles showing up to 13.0 mpg improvement.

Too much welly

The Rev. Control unit is normally set (as in the trial mentioned above) to limit maximum engine revs to the peak torque speed.  This setting gives the driver maximum power and optimum fuel economy.  A further advantage of the Rev. Control unit is that it provides a reduction in CO2 and a reduced likelihood of damage to engines and transmissions.

The resultant savings from fitting the rev limiter obviously implies that many drivers on this fleet (and others) tend to over rev their vans’ engines, wasting fuel and increasing wear and tear. This is undoubtedly true and is more a criticism of driver training than anything else — the average driver is unlikely to know the optimal revs for peak torque on every vehicle they drive, and when heavily loaded they are likely to give it a bit of welly to avoid being caught in too low a gear.

Automated solution

HGV operators have already found that the solution to this is to specify models with automated transmissions, which take the skill out of gear changes and prevent the inevitable mistakes and inefficiencies of even skilled drivers. Automatic vans are now widely available, but most van operators still specify manual transmission, due to the extra cost and perceived complexity of automated transmission.

I suspect this will change over time — not least because it will help manufacturers and operators deliver more consistent and predictable fuel consumption and CO2 emissions.

Try it and see

The Autokontrol Rev Control unit costs between £260 and £300 + VAT fitted (dependent on quantity) and is suitable for virtually any make and type of diesel or petrol engine vehicle. Stuart Gray, Autokontrol’s Sales Director, says that they are always keen to facilitate trials so that companies can work out how much benefit they will get from the system:

“Autokontrol always encourages potential customers to conduct their own fuel saving trials with any of our systems.  We support these trials by providing and installing a system free of charge and in major trials we will consider increasing this commitment.  In this way potential customers can accurately see how the UK-made product can benefit their fleet operation in terms of fuel and cost savings.”

Autokontrol also makes a range of other vehicle speed control products, including speed limits and anti-idle devices. For more information visit www.autokontrol.com.