Fuel prices have just hit a 12-month high as the cost of petrol and diesel continues to rise again. This adds to drivers’ disgruntlement over poor economy figures, despite the promise of ultra-fuel-efficient engines.
One of the most common questions from our readers remains: “Why won’t my new car get anywhere near its claimed economy figures?” The answer is the NEDC test cycle used to produce official figures is not representative of the real world, with brands optimising a car’s results.
It’s an industry-wide problem that, from 2017, will be partially fixed by a new testing regime. Despite this, though, there’s still huge disparity between what economy some drivers achieve compared with others. And these differences can often be placed down to driving style.
To find out just how much fuel we could save by a bit of eco-driving, we entered a zen state of mind, donned our lightest pair of shoes and took part in the annual MPG Marathon. Our car? The entirely inappropriate Vauxhall Maloo LSA pick-up with a 536bhp 6.2-litre supercharged V8.
With an official economy figure of just 18.5mpg, our car was one of the thirstiest at the competition, just behind a Ford Mustang V8 which claimed 20.9mpg. Over the 400-mile, two-day route, we took on the Mustang to see which car could beat its claimed economy by the biggest margin.
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To give us a better chance, we were ably assisted by Vauxhall’s archivist, navigator and resident eco-driving expert Andrew Duerden. Andrew has competed in countless fuel-economy marathons and car rallies, and as well as planning our route to the various waypoints over the two days, he would be monitoring our driving style and giving tips on how to eke out a bit extra from the Maloo’s fuel tank. He’d also brought along a sat-nav system connected to the car’s ECU, with instruments showing throttle position and engine load, allowing us to keep a close eye on how we were doing.
Before we set off from the marathon start line in Enstone, Oxfordshire, Andrew sat us down to offer some sage words of advice. “The key thing to always remember is anticipation, anticipation, anticipation,” he told us.
“You need to look much further ahead in the road and let off the throttle way in advance of any junctions or hazards. Use the accelerator and brake as little as humanly possible, and look into the distance to judge when.”
So with the pep talk ringing in our ears, we set off with a full tank of fuel. Andrew elected to direct us away from dual carriageways – where morning traffic and the Maloo’s brick-like aerodynamics could cause economy to drop – and through the A-roads and B-roads of Oxfordshire. The Maloo’s engine was fired up at the last second, and although the V8 erupted in a flare of wasteful revs, we gently pulled away without touching the accelerator. “This thing has so much torque that it can pull itself along on tickover,” Andrew explained.
This year’s marathon was dubbed “the toughest yet”, with a mixture of busy roads, town centres and motorways, aiming to recreate a more real-world commute. After we trundled away from the start at a pace that would make polar-ice movement look fast, Andrew told us we needed to quickly cycle through the gears on the open road. “Get up to as high a gear as possible and find a harmonious speed where the car feels at ease,” he said.
The car shunted agriculturally as we changed up before even reaching 1,500rpm, but once we reached 45mph in sixth gear, the Maloo settled into a relaxed drive. Maintaining this speed for as long as possible without labouring the engine was crucial for saving fuel – it’s where the car strikes the best balance between air resistance, speed and engine revs. We also needed to keep up an average speed of at least 30mph, as each checkpoint had a time limit, plus we ultimately didn’t want to be causing a safety hazard to other drivers.
Unfortunately, a string of very steep hills soon hindered our progress – it’s best to lose speed uphill so as not to work the engine too much, then rely on regaining it on the way back down. The need to maintain momentum meant cornering speeds were often quick downhill, with the instant economy readout sat at a heady 99mpg.
Junctions and roundabouts were more stressful, however. Andrew told us that coming to a dead stop was something to “avoid as much as you possibly can” because so much energy (i.e. fuel) is needed to get going again. This meant seeing the junction and slowing to a crawl, with driver and navigator looking in opposite directions to spot a gap.
Roundabouts were a more precise art – we needed to slow in advance and time our entrance into the circular flow so we didn’t stop. Sometimes, we were lucky enough to arrive at a gap that meant we didn’t need to slow down at all, but it’s important to remember that economy comes after safety. At the first checkpoint 70 miles later in Ludlow, Shropshire, we recorded an indicated average of 26.8mpg, despite some tricky sections. Other competitors seemed to be finding it even more difficult, and weren’t in agreement as to how to proceed down to the next checkpoint near Stroud, Gloucestershire. Some elected to stick to the main roads and join the M5 motorway, but we took a cross-country route.
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While we were largely on our own cutting through the countryside, a number of hills and a route through busy Cirencester hindered our progress, and we finished the day on an indicated 26.2mpg. Not only that, but the mental strain of such extreme hypermiling had taken its toll – eco-driving is far more challenging than driving normally.
For the second day, we changed tactics. Heading for the Silverstone circuit in Northants, we elected to stick to main roads and risk some motorway sections before cutting across through Silverstone village itself. Roadworks and four-way traffic lights cost us precious fuel and time, but also allowed us to practise another junction technique.
As soon as we saw a traffic light change ahead, Andrew advised us to back off the throttle and gently brake in order to leave enough space for it to turn green while the car was still moving. It didn’t always work, and we were aware that it was potentially annoying other road users.
The final two journeys – from Silverstone to Hatfield, Herts, then back across to Enstone via the A43 – finally gave us a chance to try ‘drafting’. A controversial technique favoured by many hypermilers, drafting involves getting as close as is safely possible to the back of a lorry to use its slipstream and lessen your air resistance, thereby reducing fuel consumption. It’s proven to work, but by increasing our speed to match the 57mph lorries, we found that instant fuel economy was actually reduced.
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As we arrived at our final destination, we were keen to see how we’d done. An event steward released the sealant putty around the fuel filler cap and the car was brimmed with fuel at a local filling station. Then, an RAC patrol was waiting to more accurately fill the car and ensure any air in the tank was removed, to see how much fuel we still had left in the Maloo.
Looking at the figures, we worked out we’d managed 27.45mpg overall. That meant a 48 per cent improvement on the official economy figure – leaving us as the runner-up in the ‘most improved’ category, behind the Mustang, which achieved a remarkable 36.6mpg. The highest figure recorded for a purely combustion-engined car was 88.9mpg from a Mazda 2 1.5-litre diesel, while the best overall return was 109.1mpg from a Toyota Prius plug-in.
Although we were disappointed the Maloo couldn’t take top spot, we learnt several vital lessons on our journey. Just a few tweaks to your driving style can make a sizeable difference to your fuel consumption, saving you money and benefiting the environment.
While we took eco-driving to the extreme, simple techniques, such as anticipating what’s coming up and being gentle with the brakes, are things that we can all adopt in day-to-day motoring. With practice, you might even better the manufacturers’ claimed figures.
Top 5 eco-driving tips
1. Reduce engine use at idle
Start driving immediately after starting the engine and turn the engine off if you’ll be stationary for more than a minute. For vehicles with stop/start tech, let the engine cut off if you’ll be stationary for more than eight seconds.
2. Use the highest gear you can
Accelerate up through the gears as quickly as possible, but drive at reasonable speeds, and keep the box in the highest gear you can without labouring the engine. Your engine is generally more economical at lower revs.
3. Anticipate traffic flow
Don’t accelerate or brake suddenly as you’ll use more fuel than you need to. Try
to anticipate traffic flow and coast to a stop in-gear, rather than braking at the
last minute or accelerating before you have to come to a stop.
4. Reduce weight and streamline
Remove unnecessary weight from the car – the heavier it is, the harder the engine has to work. Ditch items that cause drag such as roof bars and bike racks.
5. Keep engine maintained
Keep up with your car’s servicing schedule and ensure oil is topped up regularly. Properly maintained engines can run much more efficiently, while it’s advisable to check your tyre pressures at least once a month.