Reducing fuel on a testing run

Greener driving doesn't have to mean trading in your car for one with lower emissions and better fuel consumption

Greener driving doesn't have to mean trading in your car for one with lower emissions and better fuel consumption. Kyle Fortunesits a green driving test and finds that changing your driving habits can have a tremendous effect

YOU REMEMBER the fear don't you? That nervous, tight feeling in your stomach when your driving examiner gets into the car beside you.

I'm having it now, despite passing my driving test over 17 years ago. I'm in a Ford S-Max and beside me is Steve Docker, a friendly-looking fellow with a scary-looking laptop on his knee. As if that isn't enough there's another chap in the back, Ben Leach, who'll be taking notes on my performance.

I'm going to sit a driving examination, not one for my licence, but one to see how green my driving is.

READ MORE

I'm here with BP. Odd as it may seem, BP is encouraging us to use less fuel, even boasting that BP Ultimate fuel boosts economy by cleaning up the engine's internals. The test will take place at the Millbrook testing facility - if you've ever watched a motoring TV programme you'll probably have seen a car dramatically take to the air over one of the crests on its alpine hill route, slither around the handling track or reach its top speed on the two-mile-high speed bowl.

Sadly, there'll be no jumps, sliding about or high-speed runs this morning. Today is about driving sensibly. I'll be covering a 12.48km course that takes in Millbrook's sinuous city route (with its numerous stops and starts) and the massively undulating alpine hill route, with my drive culminating in a circuit of that high speed bowl.

I've two options really: I either drive the route as economically as I possibly can, or drive as I normally would and compare it to the best that one of BP's drivers has achieved.

I opt for the latter, as I'm really keen to see how my driving compares to the ideal. Now, I'll admit that I've got something of a lead foot, but I'm an absolute stickler for speed limits in towns and like to drive as smoothly as I possibly can.

It seems that's not such a bad start, as smoothness is one of the keys to maximising fuel economy.

Entering the comically twisty town route, I'm already aware that despite my best intentions I'm driving a bit differently than I usually would. Blame the artificial environment, or the feeling that over my shoulder Ben is scribbling away at a sheet making comments about my driving.

This stop-start city stuff isn't great for economy; little wonder so many firms are putting idle-killing systems on their cars for when they're sat still in traffic.

After the city section I head into the hills, to try some testing gradients. The ominously named 'truck slopes' catch me out first time, my reach for second gear half way up being ill advised and necessitating a quick return to first.

Going down is no less anxious; I use engine braking as I would normally, Ben saying that many people think that knocking it into neutral and coasting down is the most green way to drive. Apparently it's not.

The alpine route follows and, however tempting it is to have the tyres screeching on this brilliant, police-free, rollercoaster-like ribbon of tarmac, I drive as I would on the road.

With one exception: I'm able to take a more direct line, as it's a one-way course. This allows me to maintain momentum, be smoother and carry more speed into the dips and up the crests. A quick lap around the two-mile-high speed bowl follows, and I manage to resist the urge to climb up to the top lane for a maximum attack run, instead cruising at around 100km/h.

And the net result? Frayed nerves and 11.18 litres/100km over the entire route. I think that's pretty respectable, but I'm soon told I could have done better. Significantly so. Had I managed the perfect run of one of BP's drivers I'd have achieved the same route consuming just 8.3 litres/100km. That's a huge 35 per cent difference. Like me, you're probably thinking that to achieve such an improvement I'd have had to drive significantly slower, but that parsimonious lap was achieved within 14 seconds of my time, proving green driving isn't necessarily slow driving.

So how was it done? In my briefing I'm pleased to hear that I've actually done reasonably well. But there are many ways I could have improved. Smoothness comes into it again. When accelerating I need to do so with less haste, and once moving think about maintaining momentum. The misconception is that it's better to knock the car out of gear to freewheel to save fuel. Doing so is inadvisable as not only are you not technically in control of the car, but you're still burning fuel as the engine idles. If you're off the throttle the engine isn't using any fuel.

Anticipation is key; use the gradients to help you, try to avoid braking and try to keep the engine working in its most efficient range - that's not always the lowest revs possible. I also had the air-conditioning running, which can reduce economy by as much as 5 per cent.

Drive more sensibly and the advantages can be enormous, and it's actually quite enjoyable eking every kilometre out of your tank. Over 16,000km driving as normal I'd use an additional 463 litres of fuel and emit some 26 per cent more CO2 than if I was driving as economically as possible. And at €1.20 a litre of petrol, that's a cost of around €555.60 per year. If that's not enough to persuade you, then I don't know what is.

HOW TO DRIVE A LITTLE GREENER

CORRECT TYRE PRESSURES
Keep those tyres at the correct pressure. Under-inflated tyres are not just dangerous, but make the engine work harder due to greater rolling resistance.

KEEP IT SERVICED
A properly serviced car is vital to good green performance - engines work most efficiently when they're in good health.

REMOVE ROOF RACKS
Roof bars, boxes and racks all cause drag, meaning more fuel is used. If they're not needed, take them off.

WATCH YOUR TEMPERATURE
Use air conditioning sparingly, and keep windows closed at speed. If you're warm try the fan alone.

LOSE WEIGHT
Remove any unnecessary weight from your car; no point hauling around your golf clubs all week. Extra weight is extra demand.

REDUCE STOP START DRIVING
Be smoother in town, try to avoid rapid acceleration and avoid using the brakes.

CUT IT OUT
If you're idling in traffic for a while, where it is safe to do so switch off the engine.

LEAVE EARLIER
Beat the rush, and the traffic, and take it easier; less rushing about means less fuel.

AVOID SHORT JOURNEYS
Walk, cycle or use the bus; engines take a while to reach their optimum operating temperature, driving them short distances is not very economical at all.

CONSIDER HIGH QUALITY FUELS
Premium fuels often contain additives and cleaners that can help make them more efficient.