One of our regular readers, Elardus Van Staden, e-mailed this week regarding his 2008 Ford Territory 4.0 ST. He bought the vehicle for a song a few weeks ago, and at the time, he was so beguiled by its charms and its ability to tow the caravan he has always wanted, he never gave much thought to the fuel consumption. Now, after spending a small fortune each month on petrol, he emailed to ask what he can do to reduce his fuel consumption, which is on the sorry side of 20l/100km. He also asked if we could recommend any fuel saving devices which ‘actually’ work.

I have always believed that fuel saving devices are a complete sham. Perhaps it is the engineer in me, but my argument has always been that if placing magnets on your fuel line or remapping the ECU would really work, why wouldn’t all the major motor manufacturers be doing that? Vehicle manufacturers are under immense pressure to make their engines as efficient as possible; in certain countries there are penalties and taxes to pay for every gram of carbon emitted. Surely, these manufacturers would be overjoyed if a few simple magnets could dramatically increase efficiency and decrease consumption.

I was glad to see that my suspicions were confirmed by several reputable car magazines who performed real life tests to evaluate whether any of the widely advertised fuel saving devices work. The full article is available here, but to quote a few lines:

• South African CAR magazine showed similar results in their study of fuel saving devices. They dismissed claims by manufacturers of the airflow modifier device that placing this device in the air intake pipe supplying air to the engine will result in fuel saving of up to 15%. According to its makers, using this device will help increase power output and reduce turbo lag because the improved airflow results in better fuel mixing. But CAR’s opinion is that the device in the intake system will restrict airflow and result in worse efficiency.

• CAR also derided the claims of manufacturers of a fuel magnet that it would create a magnetic flux across the fuel pipe and change the molecular state of the hydrocarbon molecules and result in the creation of a charged state for easier vaporization and more complete combustion.

• Claims that a fuel molecule enhancer dropped into the fuel tank would decrease the surface tension of the fuel, resulting in smaller droplets which have a greater surface area exposed to air combustion for better combustion and fuel efficiency results were also dismissed by CAR.

• And finally, the claims that a fuel additive would boost combustion efficiency and raise the octane number of fuel for better fuel efficiency were, you guessed it, judged to be invalid by CAR.

CAR puts the positive reviews that can be found on product websites down to the placebo effect. Almost all these so-called miracle inventions say their product “works best” when you also avoid harsh acceleration, and drive at RPMs. Any noticeable fuel saving is actually because of these fuel-efficient driving techniques.

The only way of lowering fuel consumption is by changing your driving habits and adopting fuel efficient driving techniques. That includes driving smoother with less harsh acceleration and braking and lower speeds, eliminating excess mass and aerodynamic drag, keeping the engine in good condition through regular services, and inflating tyres to specification.

Let us examine some efficient driving techniques which can save you thousands of Rands in fuel each year, improve road safety and prevent wear on your vehicle. According to the Natural Resources Canada website, they can also lower your vehicle’s fuel consumption and carbon dioxide emissions by as much as 25%.

The harder you accelerate, the more fuel you use. In urban driving, you can use less fuel by easing onto the accelerator pedal gently. To be as fuel-efficient as possible, take 5 seconds to accelerate your vehicle up to 20 kilometres per hour from a stop.

Maintaining a steady speed will also result in a lower fuel bill. When your speed dips and bursts, you burn more fuel and more money, than is necessary. Tests have shown that varying your speed up and down between 75km/h and 85km/h per hour every 18 seconds can increase your fuel use by 20%, then driving at a constant 80km/h.

On the open road, consider using cruise control for highway driving, where conditions permit. Be mindful, however, that small variations in speed can be good when gravity does the work. Where traffic patterns permit, allow your speed to drop when you travel uphill, then regain your momentum as you roll downhill.

To maintain a steady speed, and thereby reduce fuel, always anticipate what is ahead. If the upcoming robot is red, ease off the accelerator and coast the last few hundred metres rather than driving that distance to brake sharply at the end. Keep a comfortable distance between your vehicle and the one in front of you, so that if he brakes suddenly or unpredictably, you do not have to follow suit and lose all your momentum. Become accustomed to paying close attention to what pedestrians and other cars are doing, and envisioning what they will do next, so that you can keep your speed as steady as possible and thereby use less fuel. There are also many safety advantages of driving this way.

Each vehicle has an optimum speed where they are the most fuel efficient. Of course, it depends on the vehicle and how it is geared. If your vehicle has a digital fuel consumption read out, keep an eye on it and you will soon learn what is the most suitable speed. In general, it is fair to say that above 80km/h, vehicles use increasingly more fuel the faster they go.

For example, at 120 km per hour, a vehicle uses about 20% more fuel than at 100 km per hour. On a 50-km trip, say from Johannesburg to Pretoria, this spike in speed – and fuel consumption – would cut just four minutes from your travel time.

Every time you use your brakes, you waste your forward momentum. By looking ahead at how traffic is behaving, you can often see well in advance when it is time to slow down. You will conserve fuel and save money by taking your foot off the accelerator and coasting to slow down instead of using your brakes.

6. Avoid idling your vehicle

Turn off your engine when you are stopped for more than 60 seconds unless you in stop-start traffic. The average vehicle with 3-litre engine wastes 300 millilitres (over 1 cup) of fuel for every 10 minutes it idles.

7. Measure your tyre pressure every month

Driving a vehicle with tires under-inflated by 56 kilopascals can increase fuel consumption by up to 4%. That means if your tyres should be 240 but are sitting on 185. This seemingly small oversight can also reduce the life of your tyres by more than 10,000 kilometres. Find the right tyre pressure for your vehicle on the tyre information placard. It is usually on the edge of the driver’s door or doorpost.

8. Service Your Vehicle Regularly, According to Manufacturer’s Instructions

A poorly tuned engine can use up to 50% more fuel and produces up to 50% more emissions than one that is running properly.

9. Do not carry unnecessary weight

While having the golf kit in your boot may save you a few minutes every Sunday morning, it will cost you in fuel. Remove unnecessary items your vehicle. The less it weighs, the less fuel your vehicle will use. The fuel consumption of a mid-size car increases by about 1% for every 25 kilograms of weight it carries.

10. Remove roof or bicycle racks

Streamline your vehicle by taking off the racks when you are not using them. Aerodynamic drag can increase fuel consumption by as much as 20% on the highway.

11. Use air conditioning sparingly

Air conditioning can increase a vehicle’s fuel consumption by as much as 20%. Open the windows when you are driving in the city and use the flow-through ventilation system with the windows up on the highway. If you do use air conditioning, use the re-circulate option. It will minimize the impact.

12. Use a fuel consumption display

See the impact of the all the fuel-efficient driving techniques first-hand with the help of a fuel consumption display, a feature now standard on many vehicles. Many drivers consume 15% less fuel by acting on the feedback that fuel consumption displays provide.