Step by step: how to save fuel
Operators don’t need to be told that fuel cost has a big impact upon their bottom line. But some might be surprised at just how big that impact is, and also that it’s actually not impossible to reduce it.
MiX Telematics offers a step-by-step guide that could help you achieve double-figure fuel percentage savings.
Fuel is a significant operating cost for all types of commercial vehicles. In general, the bigger the vehicle, the greater distances it will cover, and the more fuel it will burn per kilometre. While fuel may represent less than 25% of the operating cost of a small or medium van, on a heavy truck it is around 50%. Reduce a heavy truck’s fuel bill by 10% and you will reduce the operating cost by 5%. This is a worthwhile and, for some operators, entirely possible goal.
Some operators are investigating alternative fuels, such as compressed or liquefied natural gas or biogas (methane). This approach requires considerable investment in fuel infrastructure and vehicle modification, and imposes operational constraints. While some operators have been successful, others have not enjoyed such good results.
The economic case for gas is very dependent on Government fiscal policy, and were it to be widely taken up as a diesel substitute, there can be little doubt that heavier taxation would follow. It is also worth noting that, unless ‘fracking’ releases large reserves of natural gas as it has done in North America, Europe’s gas supply is through vulnerable pipelines or shipping lanes from politically unstable nations.
Vehicle manufacturers, who study such things closely, are now very focussed on fuel economy but remain largely faithful to diesel fuel. With their Euro 6 programmes complete, technical development is now concentrated on squeezing the most benefit from every drop of fuel, almost without consideration of the cost. Wise operators would do well to heed this trend and follow suit.
A total programme of fleet renewal is not an option for operators. Indeed, most will be looking to extend the service of vehicles they already have on fleet. This actually provides the cost-conscious fleet manager with an opportunity to invest in measures that will improve the performance of the existing fleet.
Currently, a vast amount of fuel is wasted on many fleets by neglecting or ignoring simple maintenance tasks: two of the most significant being paying proper attention to wheel alignment and ensuring that tyres are correctly inflated.
Wheels and tyres
Research undertaken across Europe by Volvo Trucks indicates that two out of three trucks on the road have one or more axles out of alignment. The immediate symptom is tyres that are unevenly and prematurely worn, which is an obvious unnecessary cost. There is also a hidden penalty in the extra fuel burned overcoming the increased rolling resistance. The same holds true for buses, cars and vans, although the cost of running with wheels out of alignment is less on lighter vehicles.
Figures from tyre service provider ATS Euromaster indicate that one degree of wheel misalignment on a heavy truck steer-axle will increase rolling resistance by 5% and cause a 3% reduction in fuel efficiency. Tyre life will be reduced by 7%, while the truck will be harder to drive, and severe wheel misalignment can even lead to complete loss of control in difficult conditions. Truck and trailer axle alignment does require specialist skills and equipment, but can be undertaken by mobile fitters.
Step 1: “One degree of axle misalignment raises fuel consumption by 3%.”
Step 2: “Correctly aligned axles will also improve vehicle handling and tyre life.”
Correct inflation is another area that costs operators both fuel and tyre life. It’s estimated that the average degree of under-inflation in truck tyres is around 6%, and Bridgestone, a major player in the UK truck market, maintains that the majority of its big fleet customers do not bother to check or adjust tyre pressures at all!
ATS Euromaster suggests that a 2 + 3 long-haul artic with tyres that are 10 – 20% underinflated will experience a 1.25%increase in fuel use. This figure rises to 2% if the tyres are under-inflated by over 20%. Figures for trucks on predominantly stop-start work will be worse.
> On light vans and cars, the Energy Saving Trust estimates that a vehicle with tyres under-inflated by 25% will burn 2% more fuel.
> A number of automated tyre pressure monitoring systems are now available at reasonable prices, and they can be used to either flag up a problem to the vehicle’s driver in the cab or alert the depot via a telematics link. While savings are likely to be smaller on lighter vehicles, weekly tyre pressure checks are still worthwhile on vans and cars.
> Step 1: “Tyres that are underinflated by 20% or more will raise fuel consumption by at least 2%.”
> Step 2: “Besides using more fuel, under-inflated tyres wear out faster and are more likely to suffer catastrophic failure on the road.”
> Recently introduced labels give an indication of the fuel saving qualities of different tyres across the truck, bus, van and car markets. Tyres are rated A to G, with A-graded tyres saving the most fuel.
> Independent tests by Volvo Trucks indicate that the best tyres can save up to 11% in fuel compared to the worst. However, care must be taken that other aspects of performance are not compromised by tyre choice: a drive-axle tyre offering good off-road mobility for example, will be likely to be considerably ‘thirstier’ than a road-going tyre designed purely for on-highway use. The biggest fuel economy benefit will always come from placing the most fuel-efficient tyres in axle positions that are not driven or steered (trailer axles, or the rear wheels of front-wheel drive cars and vans for example), so an effective compromise can often be reached between vehicle performance and fuel consumption.
> Careful management of truck tyres will also yield fuel economy benefits. The rolling resistance of a tyre falls as it wears, and timely re-grooving of a truck tyre extends its life just when it is using the least fuel.
> Step 1: “Fitting the right tyres may reduce fuel consumption by up to 11%.”
> Step 2: “Proactive tyre management will have other benefits as well, including reduced spend on replacement tyres, fewer breakdowns and enhanced safety.”
Airflow and drag
> Having dealt with rolling resistance, we can now turn our attention to aerodynamics. The benefits here are less clear-cut. Air resistance (drag) rises as a square in proportion to speed, so a truck that is driven only at low speed is unlikely to return any improvement in fuel consumption if its aerodynamics are improved. Indeed, the extra weight of fairings and skirts may actually make things worse.
> In research conducted by Huddersfield University, an empty tipper truck was run at 90 km/h first with its body sheet open, and then with it closed. Closing the body sheet reduced fuel consumption by a staggering 9%. But when the exercise was repeated at 60 km/h, the saving fell to 1.6%.
> Another counter-productive move is adding aerodynamic ‘aids’ that are nothing of the kind: roof top fairings to trucks where the trailer/body height actually already matches that of the cab roof, for instance.
> But most trucks cover the most distance at speeds above 60 km/h, and it is here that aerodynamics come into play. The best results always come from managing airflow over the front third of the vehicle’s length. Once it becomes turbulent, there’s little that can be done to recover the situation. This means starting with the cab. All modern truck cabs are designed with aerodynamics in mind, although other criteria including engine cooling, driver comfort, visibility and legal constraints on dimensions also have to be taken into account.
> Integrating the cab shape into the chassis and body or trailer is where the most gains are to be made, as the most turbulence is generated in these areas. Cab roof and side deflectors that ease air past the cab body junction are the most popular fitments, and for good reason: these components alone can, according to Volvo research, reduce fuel consumption by up to 8% at motorway speeds. However, the roof deflector in particular needs to be carefully matched to the body behind it: one that is 50mm too low or 100mm too high will reduce the fuel saving by 1%.
> Adjustable roof deflectors are available, including those that can be set using a remote control from the ground. But if they are specified then it is important that staff are trained in their use and given the necessary time and equipment to be able to adjust them accurately and safely if required.
> Side skirts are another enhancement: they manage the airflow around the chassis and can save around another 1% in fuel. However, they are vulnerable to damage, particularly from ‘kerbing’ or by careless FLT operators during loading. There is more to be gained from fitting them to rigid trucks and 4x2 tractors than there is on the three-axle units favoured by operators in the British Isles.
> The gap between cab back and trailer front should be reduced as much as possible, although care must be taken to ensure that the two do not clash and that axles are not overloaded as a result. This is possible on tractors fitted with sliding fifth wheels.
> Further improvements can be made by fitting devices such as vortex generators. UK supermarket Morrisons reduced its fuel bill by 2.5% after fitting Airtab vortex generators to its fleet of DAF CF tractors.
> Addenda such as roof-mounted spot lamps and air horns will have an adverse effect on aerodynamic efficiency. Similarly, racks and roof boxes increase the fuel consumption of cars and vans.
An increasing number of cars, vans and trucks are fitted with air-conditioning or climate control. While running such a system is a significant parasitic load on the vehicle’s engine, particularly on light vehicles, it still saves fuel when compared to driving with a window open at speeds above 40 mph (65 km/h).
Step 1: “Aerodynamic aids have the potential to reduce motorway fuel consumption by 8%.”
Step 2: “Many aerodynamic aids give the vehicle a better appearance and help keep it cleaner, too.”
Oils and lubrication
Lubrication technology has advanced just as quickly as engine technology. Many leading lubricant specialists claim fuel savings for their premium oils.
> Castrol, for example, has undertaken a major fleet trial in a test overseen by Quadt Consultancy of Holland. A total of 22 identical Volvo FH Globetrotters operated by Hendrickx were monitored for a period of 42 weeks, in which time they covered an aggregate distance of 0.75 million kilometres. From May to October, the trucks all ran on a high-specification 15W-40 mineral oil to establish baseline fuel consumption figures. On 1 November, all the trucks had their oil changed, with half the fleet being refilled with the mineral product and the remaining 11 switched to Castrol Elixion 5W-30 Low SAPS.
> Again, fuel consumption was monitored during the second part of the trial, and the Castrol-filled trucks returned an average fuel saving of over 4.2% against their mineral-lubricated stablemates. When the added cost of the Castrol lubricant was taken into account, there was an equivalent net saving of €1050 per truck per year for the operator. Further savings can be made by specifying high-quality fully-synthetic oils in the transmission too.
> Step 1: “Advanced lubricants have the potential to reduce fuel consumption by 4%.”
> Step 2: “These premium lubricants offer better wear protection than standard mineral oils and can often be run for extended drain intervals, saving even more money.”
> Setting a truck’s speed limiter slightly lower than the permitted maximum is unlikely to impact on journey times very much, but will produce fuel savings if routes involve motorway work.
> On smaller vans, where speed limiters are not mandatory and potential cruising speeds higher than for trucks, speed limiters can generate huge reductions in fuel consumption. Tests conducted by speed limiter manufacturer Cobra using a 2.0 litre VW van showed a 37% reduction in fuel use on roads and motorways in the English midlands when limited to 56 mph (90 km/h) against normal driving.
> Step 1: “Reduced speed limiter settings save fuel on motorways.”
> Step 2: “A reduced motorway speed will extend brake and tyre life, and may safeguard.”
> Even if your operation is not payload-critical, removing unnecessary weight from a truck will save fuel.
> Equipment that is not going to be used should be removed. Aluminium wheels and tanks are lighter than steel ones and 0.832kg per litre can be saved by not putting more fuel in the tank than is required.
> On vans and cars, the RAC Foundation calculates that every 45kgs added to a vehicle’s weight will increase fuel consumption by 2%.
> Step 1: “Lighter vehicles save the most fuel on hilly routes.”
> Step 2: “Reducing unladen weight saves fuel when the vehicle is not fully loaded, but allows extra payload when it is.”
How we travel
> Most of the above changes are relatively easily made, and will return like-for-like improvements regardless of driver behaviour.
> However, there is further scope for improvement by changing the ways in which vehicles are used. To implement and assess these changes, we need to find out how vehicles are used, and to do this we need to find out how much fuel is consumed, where and how it is consumed and what can be done to reduce this consumption by using intelligent planning and routing.
> To gather this kind of information, we need to use a vehicle telematics system. The objective here is to reduce fuel consumption without adverse impact upon operational efficiency and customer service.
Step 1: “A telematics system will measure the parameters that you need to manage.”
Step 2: “Installing a telematics system makes it much easier to manage virtually every aspect of vehicle use and driver behaviour.”
> It is easy to pursue miles per gallon or litres per kilometre as a goal in itself. This is a mistake. You could break all deliveries down into small consignments, and deliver them in little vans and you would get excellent fuel consumption figures, but a ruinous fuel bill.
> It may be that there is fuel to be saved by choosing the shorter, tougher route over the mountain rather than sending vehicles the longer, easier way around it. The only way to tell is to measure that actual amount of fuel used to get to the destination, and the best way to measure this is by using a telematics system, although operators with only a very small number of vehicles could do this as a pen and paper exercise if fuel used and time taken can be recorded accurately enough.
> Step 1: “Reducing fuel consumption overall, rather than increasing miles per gallon, is the goal.”
> Step 2: “A shorter journey, even on a tougher route, may be a quicker journey too. Accurate analysis will tell you which route is the most efficient overall.”
> Keeping vehicles away from the busiest roads at the busiest times will save fuel. A telematics system will highlight where and when regular delays occur. You may be able to persuade customers that rescheduling journeys will enable you to offer them a more reliable service.
> Step 1: “Working with customers in an open, honest way can save you both money.”
> Step 2: “Your drivers will be delighted if you can keep them out of the heaviest traffic.”
> For all the technical advances, the driver still remains the single greatest influence on vehicle fuel consumption, particularly where trucks are concerned. Most fleet operators will confirm that the difference in performance between their best and worst drivers is far more significant than that between their best and worst truck.
> Driver trainers report that improvements of 10% in the fuel performance of individual drivers after just one day of training are not unusual. The case study below shows average improvements in driver performance of 7%.
> Telematics should enable fleet managers to ascertain how wide this spectrum of performance is. Drivers can be given different routes and/or vehicles to eliminate non-human factors.
A reasonable first objective might be to get the worst drivers to perform at or close to the current fleet average. But care should be taken to compare like-with-like: a driver may do badly on fuel because he is carrying the heaviest loads on the worst roads… and making the company the most money.
Step 1: “The driver is the main variable influence on fuel consumption.”
Step 2: “Identifying the worst performers on fuel may also enable you to identify particular bad habits.”
> Formal training processes should be implemented, tackling the least economical drivers and the worst habits first. Data can be used to show that the trainer’s way is the correct way and, going forward, to ensure that lessons are learned, and that good practice continues to be implemented.
> Step 1: “The training should be delivered so it is a positive experience for drivers. Simply telling people they are doing things wrong is unlikely to improve their performance.”
> Step 2: “Focussing on a smooth and economical rather than aggressive driving style will also reduce general wear and damage, and human stress.”
> Those tasking vehicles need to be part of the process. Drivers cannot be expected to drive economically if they are constantly being badgered to maintain an unrealistic schedule. Care should also be taken in route planning so that unnecessary distances and/or journeys are eliminated. Telematics data can be used to establish realistic and efficient schedules.
> Step 1: “Good planning is the key to efficient operation.”
> Step 2: “Open and objective discussion of the data between traffic office and drivers can lead to both taking a more realistic and positive approach.”
> A truck with full fuel tanks will have upwards of £1000 worth of diesel on board. Locking filler caps can often be removed by a determined thief, but various anti-syphon devices are available. If you do fit these devices, bear in mind that a truly determined thief will just cause more damage by either tearing out the fuel gauge sender or spiking the tank if he really wants to get at your diesel, and always arrange for trucks to be parked as securely as possible.
> Ensure that vehicles are always parked in the safest possible locations, and that driver compliance is monitored. Sometimes a dishonest driver may make a pre-arranged stop where his fuel gets stolen!
> Those tasking vehicles need to be part of the process. Drivers cannot be expected to drive economically if they are constantly being badgered to maintain an unrealistic schedule. Care should also be taken in route planning so that unnecessary distance and/or journeys are eliminated.
> Step 1: “Diesel is valuable; it attracts thieves.”
> Step 2: “Secure parking places won’t just protect your vehicle’s fuel. They also help to guard against theft, and assaults on the driver.”
Fuel purchase strategies
> Fleet operators can protect themselves from some of the worst fluctuations in fuel prices in a number of ways: most notably by using fuel account cards, bunkering (paying for fuel in advance, then drawing it from participating forecourts as required) or making bulk purchases of diesel which are delivered to tanks on their premises.
> Using fuel cards is generally the most expensive way of doing things, but the advantage is that vehicles can be filled at a wide number of locations, the fuel drawn is allocated against a specific card-holder and vehicle, and that the fuel is effectively supplied on credit. Discounts are usually applied when large amounts of fuel are purchased, but the customer is exposed to fluctuations in the pump price. Fuel cards can normally be used to pay for other vehicle ‘essentials’ such as AdBlue and oil, but not for other purchases which the driver may make from a forecourt shop.
> Bunkering allows the purchase of a pre-defined amount of fuel at a set price, to be drawn from participating forecourt outlets. It’s less good for cash flow than a fuel card, but the price paid per litre of fuel is generally better. Like a fuel card, the fuel issued is booked against a specific vehicle.
> Bulk purchases command the lowest prices of all, but against that must be set the cost of delivery to premises by road tanker, and the installation and maintenance of storage tanks and delivery equipment to a high standard. Security is also an issue. Systems must be in place to ensure that the fuel ends up in the correct vehicle, and that the tanks are protected against the almost inevitable attempts at theft. Operationally this is only a suitable approach if vehicles almost always return to base to refuel.
> Whichever method, or combinations of methods are chosen for buying fuel, it’s always worth subjecting them to regular review. For bulk and bunker purchases in particular, it pays to have a shortlist of three suppliers and call them all for the most competitive price whenever more fuel is required. Many operators extend fuel card credit terms by running two or more cards, with different due dates for payment (one in the middle of the month and one at the end), and use the one that offers the longest time to pay at appropriate weeks of the month.
> Step 1: “Fuel is the most significant running cost for many transport operators. Careful control over how it is purchased is vital for business success.”
> Step 2: “Careful buying decisions can aid cash flow.”