The New Zealand vehicle fleet: fact and fiction

The inaugural New Zealand Transport Fuels Summit was held at the end of October, and the blog was invited to attend. I was able to make it to one of the two days, and I’ll try to write up some of my notes in the future.

One of the speakers was Iain McGlinchy from the Ministry of Transport, who gave a presentation on the New Zealand vehicle fleet. It was full of interesting insights – see below, or Iain’s Powerpoint for more (and much of the data is available via the Ministry’s Vehicle Fleet Statistics).

It’s often said that New Zealand has an old and inefficient vehicle fleet – but things aren’t quite as they seem. Yes, our cars are a bit older than in many other countries, averaging 13 years (vs 11 in the US, 9 in Australia and the EU, and 8 in Japan). That’s mainly down to the large number of cars we import second-hand rather than new – these mainly Japanese imports are usually around eight years old when they arrive. In particular, the ageing process is driven by the large number of cars built in 1995-1997 and imported in the early 2000s. We’ve got masses of them, and they’re still around for the most part.

What about the “inefficient” part? Iain notes that new cars tend to be safer (better features, etc) and do better in terms of particulate emissions, but “there is very little evidence that age and fuel economy are linked”. The amount of fuel used seems to come down to the number of vehicles in the fleet, and it “appears other variables, like [the] state of [the] economy, (or changes to fleet age) are not strongly affecting fuel use”.

Old cars do tend to have less efficient engines, but they’re also smaller and lighter than new cars, and they tend to do less travel. Overall, Iain thinks that “on average, if we had a younger fleet (as a result of actively getting rid of our existing older vehicles) the resulting fleet would probably have a larger engine size and travel further than our current fleet… actively intervening  to create a younger fleet to reduce CO2 emissions, would probably not work”. So, no cash for clunkers then. A lot of people don’t understand the inertia of a fleet with 3.2 million vehicles that tend to get driven for 20-odd years and do 200,000+ kilometres in their lifetime (driverless car advocates take note).

If we do want to reduce emissions – and I certainly think we should – then it could perhaps be done by encouraging cars to be scrapped and not replaced. Iain: “if fleet size shrinks as older used vehicles are scrapped then fuel use may also fall”.

One thing I found particularly interesting was Iain’s data showing that new cars claim to be more fuel efficient, but often don’t deliver in the real world. In NZ, on-road fuel use remains stubbornly around 10L/ 100 km, despite supposedly more efficient cars being sold. Here’s the data for Japan.

Essentially, vehicles have always tended to use more fuel on the road than they do when they’re being tested. But the performance gap has gotten larger (and Iain also shows this for a number of European countries). Car manufacturers are becoming very adept at designing cars to do well in the tests, but not on the road.

Iain also argues (slides 36-37) that there doesn’t seem to be much of a relationship between petrol prices and vehicle travel. I’m not sure I fully agree. There’s inertia to people’s driving behaviour too, and it can take several years for the impacts of a price hike to become fully clear. I don’t think the tailing off of vehicle travel in the mid-2000s can be explained by much else except the massive rise in petrol prices – it’s not like the government started investing in public transport or anything, right?

Iain also asks the question that if most of our cars come from Japan, and the cars there are getting more efficient (and they are, despite the “gap” above – there are various incentives and subsidies in place there for hybrids and other efficient cars), will NZ’s fleet get more efficient too? The answer is, not necessarily. Japan favours small cars and hybrids, whereas here in NZ we continue to import medium/ large cars and SUVs. And hybrids tend to stick around for longer in Japan, due to the incentives, so it’s hard for NZ car importers to buy them at competitive prices.

Finally, Iain wraps up by discussing things that could help improve New Zealand’s fleet fuel economy/ emissions/ safety and so on. These include hybrids, Intelligent Transport Systems (not so sure about these; people can view this kind of stuff as an invasion of privacy or civil liberties, which is why we have so few speed and traffic light cameras), better network efficiency (ramp metering signals etc), improving driver skills, and, of course, “reducing use of motor vehicles”. I’m sure there are a few positive actions we could take on that last point.

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