Petrol Efficiency Experiment: An increase of 20% without increasing trip length.

In the cheapest petrol article, as well as how to find and pay for petrol the cheapest way, there are top tips for driving more efficiently to cut petrol usage. I recently had the opportunity to test it for myself for the first time. On Christmas holiday in South Africa (and before you ask, yes it was a cheap flight, we hired a car (and yes it was from the cheapest car hire!) which had a digital display of fuel efficiency. Now as anything with changing numbers on it appeals to me; I decided to use the trip as an experiment (and yes I’m a nerd).

Before I explain the experiment it’s important you understand my normal driving style. I’m not a boy racer; I don’t accelerate away from traffic lights and brake hard at the next one (the most inefficient and expensive way to drive). Fuel efficiency is something I generally take notice of, though as I drive a little Smart car it’s pretty good anyway.

The parameters of the experiment

Thus as I already drive pretty efficiently, the aim here was to find out if by being ultra-conscious of every time I put my foot on the accelerator, I could increase my driving efficiency. So on every journey we made, I reset the ‘trip average’ button and measured the fuel efficiency of the journey.

On one leg I would drive normally, on the other I would drive with a real focus on use of gas, remembering every time I put my foot down it used fuel. To ensure the accuracy of the experiment I varied whether it was the outbound or return journey to ensure that any height differences between destinations would be even out. The trips were a mix of urban and extra urban areas.

The results were phenomenal

On every trip there was a substantial difference between the number of Km per litre I got using my different driving heads. After totting it up; the average was as follows:

  • Normal driving method average: 11.2 kilometers per litre
  • Efficiency-conscious driving method: 13.4 kilometers per litre.
  • This is a saving of £440 a year!

    This mightn’t look a big difference until you look in terms of percentages. This is a 20% increase in efficiency. For someone who currently spends £50 a week on fuel the cost would reduce to £41.50 a saving of £440 a year! And remember, this is for a normal driver; those who like to razz their cars would spend more.

    The impact on my speed

    What surprised me most was that it had very little impact on the time taken to get there. The two main ways of doing this are when coming to a junction; rather than just braking I let the car slow down more naturally, but it didn’t mean I lost track of the car in front. Also, when accelerating I did so more slowly, keeping the revs down, yet overall getting to the same speed, just using much less power.

    The one major difference was I had to be much more aware of the fact I’m driving, rather than putting the mental auto-pilot on as most of us do. Though again, actually for safety’s sake this was good, as I was much more aware of the road and cars around me than normal.

    I would be fascinated to hear if anyone else has tried this; or maybe will now after reading it.

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