How to save on fuel

My recent research into car fuel economy has turned up some surprising findings. It looks like more may mean less and it is possible to save on the gas bill without turning the ignition key.

If you have been following the competitive automotive market in the last decade or so you cannot have missed the emergence of small turbo-charged engines. The theory underpinning their claimed efficiency is solid. If you drive them leisurely they are just small engines which, due to lower internal inertia and friction, burn less gas. But if you need to accelerate quickly the turbo kicks in producing the required power boost. A large displacement engine on the other hand suffers more losses to overcome the inertia and friction of its moving parts while the full power it is capable of producing is only called upon infrequently. This is why the laboratory tests used to derive the “official” fuel economy figures consistently show that small turbo cars outperform larger, atmospheric engines. Very logical, right?

Right, except this is not how people drive their cars. A comprehensive survey of the fuel consumption in real life has revealed two startling facts, summarised in the graph below.


  1. The difference between the claimed and actually realised fuel economy is much greater for smaller engines
  2. The real life fuel consumption of small engine cars is worse than both medium-sized and large engines

The reason is that most users push their car far beyond what the official economy tests do which changes the rules of the game considerably. Thrashed small turbo engines have to work very hard to produce the required power way outside the optimal range of their operating conditions. But larger displacement engines tolerate being pushed hard a lot better and, on the road, deliver better mileage. Additionally, the stop-start systems which stop the engine when car comes to a standstill do very little to improve real life fuel economy – they were invented purely to take advantage of the numerous stop-start sequences in the official laboratory testing regime.

Ok, so if we cannot save fuel by choosing a car with a small turbo engine what can we do? Before you look at exotic tricks like over inflating tyres consider the number one recommendation published by The Telegraph:


Yes, the most effective way to save on gas is very low tech – do not turn on the ignition! Plan your day to minimise car trips, purchase whatever you can online not at the counter, do groceries on the way back from work (and do not forget the bread – otherwise you will have to make an extra trip).

Despite the remarkably complex technology available these days some things in life remain simple.


One Response to “How to save on fuel”

  1. Voytek Klepatski Says:


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