Fuel consumption: fewer vehicles means less than fewer emissions

So, school holidays are coming to an end.  My son is breathing a big sigh of dismay. And, like so many other commuters, so am I. I’ve enjoyed two weeks of being able to get to and from work (especially the ‘to’) without traffic hold ups and ‘having to go the long way around’.  My 23 km commute from Cambridge to Hamilton goes from about 32 minutes average to about 23. (I hear many of you Aucklanders or Wellingtonians saying …”32 minutes: is that all?…”)

The point I want to make is about fuel consumption. My Toyata Yaris is pretty economical as petrol cars go. It’s got a fuel consumption gauge on it – I reset it everytime I fill up and it tells me the average litres per 100 km I’ve done since I last reset it. During school term, consumption is around 6.1 litres per 100 km.  In the last couple of weeks, it’s averaged 5.4 litres per 100 km – that’s ten percent less fuel used getting around than in school term. The savings come from being about to take the direct route up SH1 rather than the route up SH1B and then through Matangi in order to avoid the looonnnngggg traffic jams by Tamahere; this is (a) shorter and (b), because the looonnngggg traffic jams don’t exist, I can cruise at 80 – 100 km/h for much of the journey rather than start and stop.

So, assuming that other cars behave similarly, one can conclude that halving (say) the traffic on the road will more than halve the total emissions. Or, extrapolating the other way, an increase of journeys by (say) 20% will lead to a more than 20% increase in total emissions.  There is good reason to get traffic off the road.

On an aside, I read this blog last night about why you have already bought your last car. Such is the disruptive power of electric vehicles, self-drive vehicles and uber-style scheduling, Justin Rowlatt suggests (he admits at a stretch) that in ten years it will be cheaper to call up a self-driving electric uber everytime you want to travel than to own your own car, and this cold, hard economic fact (not climate change) will make the privately-owned internal combustion engine a thing of the past much sooner than we might think. Have a read – I particularly like the Fifth Avenue New York photos – in 1900 it was all horse and no car – in 1913, just 13 years later, it was all car and no horse.


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