Moves are afoot to produce fuel economy estimates that more closely reflect what people can expect from vehicles, writes Tim O'Brien
That sleek new 55-miles-per-gallon car you have been eyeing up for 2007 may turn out to be a 44-miles-per-gallon car if you wait until January 2008, it has emerged.
That is because moves are afoot around the world - particularly here in Ireland - to come up with mileage estimates that more closely reflect the real-world mileage people can except when they purchase a vehicle.
Currently, the fuel consumption grading is determined by manufacturers in near laboratory-like test conditions and while this may prove a useful standard when comparing one car to another, the actual fuel economy achieved by the owner is usually considerably less in real terms on the public road.
This is simply because once the car leaves the manufacturer new drivers impose a variety of new conditions, including differing tyre pressure, the use of air conditioning - which alone can affect the car fuel performance by about 10 per cent - the driver's use of accelerator and brakes, even leaving the windows open or using a roof rack.
Then there is the fact that urban driving conditions may vary considerably between Dublin's M50 and Munich city centre, with traffic and fuel consumption considerably lighter in the latter. So too rural roads in Ireland may be considerably different terrain than rural roads elsewhere.
In the US, the federal Environmental Protection Agency (EPA) has already announced a new system for evaluating fuel economy that will use real life conditions, and as a result will lower mileage estimates for most vehicles by about 12 per cent in city driving, and eight per cent in rural mileage.
In Europe the Brussels-based European Transport Safety Council, an independent body of motoring organisations that includes Ireland's AA, is also set to look at the creation of a new, independent fuel economy index.
The council has had a lot of success in recent years in setting up independent standards for crash safety and while this was initially resisted by some individual carmakers who wanted to rely on their own testing, the council's system is now an industry standard used even in carmakers' advertising.
According to AA Ireland the council will address the question of independent fuel consumption testing later this year. At the same time the AA is to raise the issue with the Government in the Republic as part of the review of motor and vehicle registration taxation announced by Minister for Finance Brian Cowen in the Budget.
The AA is currently preparing a submission to the Government on the tax changes and will argue that, particularly in relation to the change from tax based on engine size to tax based on emissions, that a more realistic index of fuel economy is a necessary starting point. The deadline for submissions is March and the Government has said it hopes to include changes for the 2008 fiscal year.
In the United States, vehicles rated under the new "on-street all weather conditions" standard test recorded a 12 per cent drop in city-driving mileage and an 8 per cent decline in highway mileage, according to Bill Wehrum, the EPA's acting assistant administrator for air and radiation.
Hybrids were hardest hit by the change because the new standard test eliminates some of the all-electric driving that helped them post impressive results under the older system.
If the Toyota Prius, for example, was not allowed to include the city mileage powered by its electric batteries in its fuel consumption figures, its miles per gallon figures would look very different.
Toyota in the United States however supported the new system, pointing out that it did not change the fact of the cars' electronic capability.
The Department of the Environment is currently devising a simplistic colour-coded CO2 rating system - similar to that used to rate white goods.
From 2008, motorists can expect to see new cars colour-coded with yellow label cars producing the least CO2 and red label ones the most. In the US this was the system used to display ratings of fuel economy.
Cyril McHugh, chief executive of the Society of the Irish Motor Industry, said he is unaware of moves to change the consumption measurement system, pointing out that fuel efficiency in cars had increased "dramatically" in the last 10 years, and the current system was still a useful tool for making comparisons between new vehicles. The emissions from one car built in the 1970s would be equal to that of 30 modern cars, he added.
But AA spokesman Conor Faughnan said a change was necessary, particularly in the light of the Government's proposed tax changes. "If we are to have an emissions-based tax, it would make sense that we knew what the real consumption figures were. I do think the current figures are a useful standard for measuring one car's efficiency against another, but if you want to get real fuel consumption, and so emissions figures, you have to devise a new way of doing that."- (additional reporting LA Times)
