Common Urban Myths About Transport

Myth: Cars are becoming more fuel efficient

Fact: While it's true that engines get steadily better at using fuel, people have responded by buying more fuel-hungry cars. As a result, the average efficiency of the Australian vehicle fleet has not changed significantly since figures were first collected in 1963.

Hopes that car use will become more sustainable through better fuel economy are widespread, and often exploited for political advantage. In 2007, for example, State Treasurer John Brumby used this myth to defend cuts to stamp duty on large new cars:

I think it is generally accepted that newer cars are certainly much cleaner, as I said, much safer and generally more fuel efficient - not all of them, but generally more fuel efficient.... I certainly believe that there will be very positive environmental benefits from getting people out of old [cars].... and getting them into new cars.
---John Brumby, Victorian Hansard, May 2007

Such hopes have been likened to walking down an 'up' escalator. Even if vehicles become on the whole more fuel efficient, motorists can be expected to respond much as they would to a drop in petrol prices: by driving further and more often.

However, there is little indication that the cars we actually drive are becoming any more fuel efficient. In Britain, the Royal Commission on Environmental Pollution found that, while the fuel economy of new British cars improved during the oil shock of the late 1970s and early 1980s, fuel economy has actually worsened since then.

Australian figures for fuel economy tell a similar story. For some decades, the Australian Bureau of Statistics has conducted a Survey of Motor Vehicle Usage, which estimates the average fuel consumption of all Australian passenger vehicles on the road. This figure has hovered slightly above or below 12 litres per 100 km over the entire period for which data have been collected. The most recent available figure (from 2006) of 11.4 litres/100km is identical to the very first figure collected over four decades earlier!

Year	Average fuel efficiency (passenger vehicles)
1963	11.4 litres/100km
1971	12.3
1976	12.6
1979	12.5
1982	12.5
1985	12.1
1988	11.9
1991	12.3
1995	11.5
1998	11.8
1999	11.7
2000	11.9
2001	11.4
2002	11.3
2003	11.4
2004	11.5
2005	11.7
2006	11.4

The same ABS data tells us that cars purchased since 2000 have an average fuel efficiency of 12.1 litres per 100km, one litre higher than the average efficiency of cars purchased between 1990 and 1999, of 11.1 litres per 100km. So despite what John Brumby might say, it is clear that newer doesn't mean more economical.

It is likely, as transport researcher Patrick Moriarty argues, that improvements in engine efficiency over the decades have been offset by other factors: the trend toward larger vehicles such as four-wheel-drives, increased use of air conditioning, electronic control components demanding greater power input, ageing of the car fleet, and compromises required to reduce air pollution.

Just recently, hybrid petrol-electric vehicles have hit the market amid a flurry of marketing hype that promises astounding fuel efficiencies, with ads promising that you'll only have to visit a petrol station once a year or less. But in America, even hybrids are following the same old trend: the improvements in engine efficiency are being used not to reduce fuel consumption, but to put more 'grunt' under the bonnet.

Mark Buford is happy with the Honda Accord hybrid that he bought six months ago, and he has already driven it 13,000 miles. He was determined to buy a hybrid electric car, he said, and this one is clean, 'green' and accelerates faster than the nonhybrid version. He just cannot count on it to save much gasoline.
....Hybrid technology, it seems, is being used in much the same way as earlier under-the-hood innovations that increased gasoline efficiency: to satisfy the American appetite for acceleration and bulk....
Consumer Reports, in an article published in May, found that in actual on-the-road conditions the Accord hybrid averaged 25 [miles per gallon], versus 24 m.p.g. for the 4-cylinder model and 23 m.p.g. for the nonhybrid V-6....If every car in the country were converted to a hybrid with that improved mileage, the gain would be swallowed up in three to four years by growth in driving demand.
---"Hybrid Cars Burning Gas in the Drive for Power", New York Times, 17 July 2005

Australian market trends seem likely to follow the American pattern. Like the Americans, we have seen our cars increase steadily in weight and engine power in line with improvements in engine technology. After all, what new car buyer can resist a bigger and more powerful car that costs the same to run as their previous vehicle?

This is also why glowing reports of new hi-tech 'ultra-efficient' cars like this one are of little relevance to the urban transport problem (at least until petrol is much more expensive than it is now). Quite simply, the factors that make these vehicles highly efficient also make them less attractive to the typical motorist. The world record for vehicle fuel efficiency has already been set for all time by the bicycle, which has infinite efficiency since it requires no fuel at all. A motorist who wishes to maximise their fuel efficiency would be well advised to just switch to cycling. On the other hand, a motorist who finds riding a bike unattractive is unlikely to be attracted to these ultra-efficient vehicles for much the same reasons.

When it comes to the environmental impact of each 'unit' of car use, in particular greenhouse emissions, things have not actually stayed the same but have actually got slightly worse over time. This is because the catalytic converters found in newer cars, while reducing some emissions from unburnt fuel in the exhaust, also increase emissions of some chemicals like dinitrogen oxide (N₂O) which act as local pollutants and also happen to be potent greenhouse gases. Thus, the average greenhouse emissions from each kilometre travelled in a car have increased by about 5 per cent between 1991 and 2002, or by 8 per cent for car travel in urban areas.

	Car emissions (grams CO₂ equiv per passenger-km)
Year	All car travel	Urban car travel
1991	169	177
1995	168	186
1998	175	189
2002	178	192

Source: Australian Greenhouse Office. National Greenhouse Gas Inventory: Analysis of Recent Trends and Greenhouse Indicators 1990 to 2002.

As the National Greenhouse Inventory also reminds us, the total passenger-kilometres travelled in cars has increased by 18 per cent, and vehicle-kilometres by 25 per cent, over the same period (1991 to 2002). Vehicle-kilometres have grown faster, because each car now carries fewer passengers on average than in 1991.

As Paul Mees concludes:

Per capita travel by car by residents of Australian cities doubled between the early 1960s and mid-1990s, and so did the urban population. The 'up' escalator of travel growth has run at high speed, while the downward effect of improved technology has been nonexistent.
---Mees, A Very Public Solution, p.61

Or, as a Canadian journalist summed it up:

I don't need to run out and buy a hybrid car out of guilt.... I can certainly hang up the keys more often and probably achieve the same effect.
---Lorraine Sommerfeld, Hamilton Spectator (Canada), April 2007

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Last modified: 21 May 2008