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SPRINT TO SAVINGS
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No operator can afford to waste fuel, so we were intrigued by rumours of Sprinters set up to cut consumption for minimal cost.
Colin Barnett put the technology to the test and recorded savings of more than 45%...
perators of heavy trucks are well aware of the costs of running their vehicles, but the running costs of vans arc not always as closely scrutinised.That's not to say significant savings aren't available — we've been trying out a couple of low-cost solutions from Mercedes-Benz that could have a significant effect on your bottom line.
The Mercedes-Benz Sprinter has become the byword fora white van barrelling down the outside lane taking no prisoners. With power levels on tap that would satisfy a 7.5-tonner, there's no doubt that if you need to get your products from Dusseldorf to Munich before the sun comes up, this is the van to do it. But on this crowded island, all those horses are harder to justify.
Thanks to EU Directive 2002/85/EC, some new vans over 3,500kg GVW on international journeys have been limited to 56mph since the beginning of 2005; used vans registered after 1 October 2001 joined them at the start of this year, and new vans on UK operations will need to be limited from the beginning of 2008. But there are no plans to extend the limit below 3,500kg.
Putting the legal and moral aspects to one side, there's another issue that's convincing some of the biggest van operators in the UK to fit speed limiters before the law requires them. With the £4 gallon with us already and the £5 gallon just one scare away, reducing the speed of vans is one way of saving fuel.
What's more, you don't need expensive add-on hardware to limit your Sprinter's top speed— Mercedes will do the job electronically in less time than it takes to drink a cup of tea, for a quoted price of i70. A number of bluechip van fleets, especially in the parcels sector, have already taken this route.
To quantify the effect of speed limiting on fuel economy, we took a couple of Sprinters to the controlled environment of the Millbrook Proving Ground in Bedfordshire for two sets of tests: one to establish fuel consumption at constant speed: another to simulate more realistic conditions via a mixture of steady speed on the high-speed bowl and variable speeds on the hill route.
For the first test we used a couple of mechanically identical Sprinter 313 CDI vans loaded to half their maximum payload.The procedure was simple enough: we fuelled up at Millbrook-s own filling station and proceeded to the high-speed bowl at a sedate 30mph.
For the first runs, the vans were electronically limited to a GPS-confirmed 75mph (at 3,000rpm).We did 10 laps of the two-mile howl in each van flat out, before returning to the fuel station and taking a brim-to-brim fuel measurement, carefully monitored by a Mercedes technician.Then the process was repeated at 60mph (at 2,2(X)rpm).
The lower speed cut a fuel consumption by 39.8% on one van and 35.1% on the other, giving a fair indication of the fuel penalty involved in high-speed cruising.
Our second test was intended to reflect the effect of different driving styles on mixed operations. We devised a route at Millbrook made up of 10 laps at a steady speed, followed by five further laps of the challenging hill section. About 70% of each of these laps consisted of two hill ascents and descents, with 30% on fairly flat link roads.This time.only one of the vans was used.
The first run involved cruising at 80mph, which experience suggests is not unusual on a motorway, even for a 3.5-tonner.The hill section was also tackled rapidly (but not ridiculously so), with little regard for speed limits.
After refuelling, the test was repeated with a 60mph cruise and a rather more restrained driving style on the hill route.
We naturally expected this (admittedly less scientific) test to prove that driving style affects fuel economy, but even so we were surprised by the results.
The fast run used exactly 46% more fuel than the more sensible run. Obviously, fuel savings are offset by increased journey times. and the slower driving style stretched the journey time by 16.2%.
The productivity issue these numbers raise is complicated and depends on other factors. On one hand, the amount of work possible in a day is ultimately less, but this is countered by reductions in wear and tear and running costs, both of van and man. We can't answer all your questions, but hopefully you can factor these figures into your own operations.
The cost of idling YO U could easily think that an idling engine uses little fuel, but read on. We recently had a graphic demonstration of this after an easierthan-expected early-morning drive from Sussex to Luton left us with an hour to kill. As it was a cold dark morning, the obvious thing to do was to park up and catch up on a bit of sleep. After an hour of leaving the VAG TD1 on tickover with the heater and heated seats keeping the frost at bay, the fuel economy for the journey had dropped from around 58mpg to less than 48mpg.
Since then. we've had more scientific confirmation of this by trying out a pair of M-B Sprinters in heavy traffic.The two half-laden 313 CDIs were mechanically identical except for one being equipped with the MSS engine stop/start system. This stops the engine when the van is stationary, restarting it when the clutch is depressed ready to move off.
The system won't operate until a certain coolant temperature is reached,ensuring that starting will be near-instantaneous and that the battery has recovered from the initial cold start.The engine will only stop when the van has stopped moving, neutral is selected and the clutch is effectively released. though there is a short period of clutch travel at the top which allows fine control once you get to know the system.
The engine restarts automatically when the clutch is depressed more than an inch or so, or when the van is rolling backwards or forwards for more than a moment.An interlock prevents the engine from self-starting when the bonnet is open. There is very little in the way of controls for the driver to learn, apart from a system on-off dash switch and a dash warning light to show that MSS is engaged and about to do its stuff. the most important driver input is to ensure that neutral is selected and the clutch released at every opportunity, and this might require suitable motivation.
For our comparison, we did something no sane person would do — venture into London in the rush hour.The route began at Rossett's, M-B's CV dealer in Crawley, and headed via Tooting and Hammersmith to a destination where we knew blessed relief would be available, the Ace Cafe just beyond Hangar Lane on the North Circular.
Urban operation The route measured just 41 miles: readers lucky enough to live a long way from the capital may be amused by the fact that the run took 206 minutes, an average speed of 11.9mph.This was despite an easy first 10 miles on the run up the M23, when the only thing of note that happened was being overtaken by another vehicle from the Mercedes press fleet, a McLaren SLR.
Even the ridiculous Hooley junction (where a three-lane motorway shrinks to a single-lane residential road) passed with no delay, but the situation soon changed as we joined the queue through the Coulsdon bypass works.After that. there were barely two consecutive minutes of clear running until we reached our destination. The system did exactly what it says on the tin, shutting down the engine approximately two seconds after the clutch is released and restarting as required. The only downside was the fluctuation in heater output with the engine off and the interruption to the radio while the engine was cranking.
The fuel consumption of the MSS van was 35.7mpg, while the control van (driven in as similar a style as we could arrange) used 30% more fuel to record 27.5mpg.Although the savings will always be as variable as the operating conditions, in general worse traffic will bring bigger savings. We're convinced that at £175 on the cost of a new vehicle. MSS makes economic sense for urban operations.M-B (UK) is working on a retro-fit kit which is likely to cost a bit more, hut should still be viable.
Indications from the residual forecasters are that MSS will more than recoup its premium at resale time. It is now available on all manualtransmission Mercs up to the Actros — one operator of middleweight trucks intends using it to prevent excessive idling time.
We've looked for downsides, but apart from how you motivate drivers to use it, there don't seem to be any. We expressed concern about the effects of MSS on starter-motor life but information from Switzerland. where it has been standard equipment for a few years, reveals no problem within the three-year warranty period.And with these potential fuel savings, the cost of a new starter motor every three years would still be peanuts. •