Under the Choko Tree By Nevin Sweeney

Save Fuel, Save Money

I have been facilitating a study circle with a few friends based around the various aspects of sustainability. One of those aspects is, of course, transport and we talked about among other things the issues with car use (greenhouse gas production, fossil fuel use and consumption of other resources).  Discussions around car use generally seem to find their way back to how much fuel we consume and what we can do about it.

Our circumstances (unfortunately) do not allow us to dispense with the car entirely so it was a case of understanding what we could do to reduce the amount of fuel we used in a meaningful way. This would not only reduce environmental damage but save money as well and as a result of the meeting we all agreed to do some work towards reducing our fuel consumption and then report back. This is what I did and how it worked.

Measuring the Base Line

Strange as it seems, to be able to work out how much you have improved this means knowing where you are starting from, so my first act was to fill up the car and note the mileage (kilometerage?) on my odometer. I then drove the car for a couple of weeks without making any changes to the car or my driving behaviours so I could work out where I was now.

We drive a Suzuki Alto and the manual says I should get 5.3 litres/ 100 kilometres, but these official figures tend to be pretty optimistic, and I needed to know what I was really getting. I filled the car up (first click on the nozzle only, fill to the same point every time for consistency) and took note of the mileage on the odometer. It was then just a case of doing what I always do and driving around as normal.

After the tank was getting down towards empty I filled the car up and noting the number of litres consumed and I checked the odometer again, writing down the reading.

To calculate your fuel consumption in L/100km just take the original reading on the odometer away from the second reading to give you the number of kilometres travelled, then multiply this number by 100, divide the resulting figure by the number of litres of fuel consumed. (or use an on-line calculator). This will give you your fuel consumption in L/100km. Mine turned out to be 6.4 litres/100km.

The longer you let the test go on the more accurate the reading will be, but I wanted to know what affect I could have quickly (I’m impatient OK?) so this would do me.

Making the Changes

There are a whole stack of changes you can make to your car and your behaviour to reduce fuel consumption, as far as making changes to the car you could –

• remove any unnecessary materials/weight from the car
• remove roof racks, external steps and brush guards when they are not required, to improve the cars aerodynamics, and
• Ensure the tyres are pumped up to the required pressure (not overpressured)

In terms of behaviour, changes might include -

• driving steadily, at or below the speed limit (operating speed)
• using the cruise control where possible
• accelerating smoothly to operating speed
• avoiding idling and turning the engine off where idling time is likely to exceed one minute.
• going slower up hills and faster down hills (within the speed limit)

When I checked the car over I found the tyres were down a bit so I pumped them up. We get the car serviced regularly, rarely carry a lot of extra weight and don’t have roof racks or other protrusions to screw up the car’s aerodynamics. In terms of behaviour I am, as much as is possible with a car with an engine capacity of 996cc) a rev head! I needed to slow down, drive more smoothly and concentrate on driving to minimise acceleration and braking. (yes, I am that idiot who hares up behind you then jams on the anchors, stupid, I know).

Well, I made the changes to my behaviour. It wasn’t easy, there is always the tendency to slip back into old habits and after all, I have been driving for almost 40 years. Having a wife who supports the changes and is not shy in pointing out when I am doing the wrong thing helps. Sort of. You know how they say your fuel consumption goes up if you drive stressed?

Anyway, I know you are dying to know how it worked and it reduced my fuel consumption to 5.5 L/100km, a reduction of almost 15%. This was achieved at no extra cost to me (how do you cost in grey hairs?) and is a significant saving on fuel and cost. Just working out your fuel consumption on a regular can help you focus on your driving and how it affects your mileage, so start today!

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