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Flying is two times more efficient than driving

Believe it or not, it is much more efficient to take a plane than it is to drive. Not only that, the gap in energy intensity has widened considerably.

Back in the 1970s it was more efficient to take the car, but in recent years the balance has tipped in favour of air travel to the point where a car is 2.07 times more energy intensive.

That is according to a study of new figures by Michael Sivak of the University of Michigan Transportation Research Institute, which found the energy intensity of driving was 71 per cent greater than an average domestic flight in the US.

A ‘light-duty vehicle’ like a car or small van manages an average of 21.6 miles per gallon, which would mean a car would have to average 44.7mpg to have the same average energy intensity as a plane. No doubt America’s fascination with the V8 is playing a role in that woefully low figure.

The maths behind the study actually disregards plug-in hybrid and all-electric vehicles like the Tesla Model S so the US average mpg could be more favourable, although with just a 1 per cent share of the whole US market in 2012 it is unlikely the figures would be skewed much.

Besides aircraft being able to hold many more passengers, Savik pointed out that the average car journey length in the US is 9 miles, far shorter than the average plane journey, which is 895 miles. He did, however, admit both modes of transport serve “two different general purposes” and so both are necessary.

The study also pointed out that fuel economy for both cars and planes gets better as the length of journey increases, adding that as much as 25 per cent of fuel for a plane journey is used during take-off. Improvements in aircraft efficiency and the adoption of more eco-friendly vehicles will play a role in improving the situation.

It’s worth noting the energy intensity figure assumes 1.38 people in the car, which means a car easily outdoes a plane when you start cramming people in. But – and this is the crux of it – 1.38 is the average number of people that use a car.

Ultimately the information highlights a fact we already know, that we have to use cars for short journeys and planes for longer ones, but getting just one extra person in the former would certainly make car journeys less wasteful.

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