Our initial drive in a Sprinter 313CDI 3.5-tonner with a 500kg test load on board took us part-way round the perimeter road of a huge former army base and training ground to the south-east of Stuttgart. To simulate real-world driving the route included road works and temporary traffic lights.

Conscious that we were supposed to be driving with minimal fuel use in mind, we took a gentle approach to our first economy run. We didn’t screech away from the lights as usual, changed up a gear whenever possible, switched off the radio and the heating and ventilation system’s booster fan, and only applied the gentlest of pressures to the accelerator pedal.

The result of this approach was that while our fuel economy was reasonable at 28.6mpg, our progress was too slow. It took us 41 minutes to drive 18.5 miles at an average speed of just under 27mph. CO₂ emissions for the run stood at 259g/km.

Different Strokes

Having listened to the theory of economic driving, and to the advice of our instructor, we approached our second run over the same circuit rather differently. In particular, we used the van’s kinetic energy. In other words, when descending inclines we left the van in gear and the loud pedal well alone, only touching the brakes when we felt we were going downhill too fast.

Furthermore, we adopted a more optimistic policy when changing up. Slopes that we had previously attempted in third gear were tackled in fourth instead. Sprinter happily trundled up them, with no loss of performance.Mercedes stresses that an engine requires less fuel at a low engine speed in high gear than it does at a higher engine speed in a lower gear.

We also put the heating and ventilation system’s booster fan on, plus the radio. “Lower fuel consumption should not be achieved at the expense of comfort or, for that matter, safety,” says driver training instructor Klaus Buhl.

Start/Stop

Something that made a big difference to our fuel consumption second time round, however, was the use of something called ECO start/stop.

Stop at the traffic lights and put the gear lever into neutral and the engine cuts out after three seconds, saving diesel and eliminating exhaust emissions and noise. Dip the clutch and engage first gear when the lights go green, or release the brake so that the van starts to roll forwards, and the engine fires up again.

The headlights and the heating and ventilation system keep working while the engine is off and ECO start/stop is deactivated when the vehicle’s battery voltage is low. Flick a switch on the dashboard and you can turn the system off should you so wish.

Fuel-Saving

Capable of cutting average fuel consumption by up to eight per cent on urban trips according to Mercedes, and even by as much as 20 per cent in really heavy city centre traffic, ECO start/stop is a £500 option on all Sprinters with four-cylinder engines. However, it costs just £250 if you specify air conditioning.

That’s because both ECO start/stop and air con require a bigger battery and alternator. Opt for air con and they’re included in the deal, so if you specify ECO start/stop too you don’t have to pay for them twice.

The net result was that we completed our second run over the same route in 36 minutes at an average speed of 30.5mph. This time round we averaged 29.7mpg.

Second time round we changed gear 118 rather than 170 times and CO₂ emissions stood at 248.85g/km. Given that ECO start/stop had such a significant impact it would have been interesting to see what the difference in mpg between the two runs would have been if we had tackled them both without using it.

Mercedes is highlighting the virtues of driving training in tandem with the launch of BlueEFFICIENCY. The logo denotes Sprinters fitted with ECO start/stop and models powered by natural gas.

At the same time Mercedes is spotlighting the fuel efficiency of the engine and transmission packages deployed in the recently revised Sprinter. The six-speed ECO Gearbox has a high overdrive top gear designed to cut diesel usage on the motorway.

A BlueEFFICIENCY concept Vito was exhibited at last year’s Hanover Commercial Vehicle Show with an aerodynamic package, low rolling resistance tyres and small externally-mounted cameras rather than big, wind-resistant, exterior mirrors among other features.

The manufacturer’s view, however, is that drivers will only get the best out of the latest technology fitted to its vehicles if they are shown how to use it. Mercedes light commercial customers can avail themselves of a variety of different training packages organised by the manufacturer, which recently opened a brand-new driver training centre at its Wentworth Park site just outside Barnsley.

Verdict

While What Van? is wholly in favour of training van drivers to drive more economically, any training programme has to be accompanied by some sort of incentive scheme. The most frugal driver should receive a monthly, quarterly or annual cash bonus, plus some sort of recognition from their employer; a trophy, say, or a certificate. If that’s not practical because of the way in which the firm operates, the award should be made to the most economical group of drivers; drivers based at a particular depot, or working on a particular contract. Furthermore, training should be conducted regularly. Employees can gradually revert to bad habits; and the turnover of drivers at some companies means that more and more people who have received no training at all can end up behind the wheel during the course of a year.