It should come as no surprise to anyone paying attention that the fuel economy of vehicles in the real world seldom comes close to the official ratings advertised for them.
If rumblings from within Canadian government offices are to be believed, that situation may be about to change.
The issue of the differences between advertised and real fuel-consumption has become news again because of a highly publicized complaint from a Calgary couple against General Motors.
The couple say they feel misled – even cheated – by GM because their 2011 Chevrolet Cruze doesn't achieve the fuel-consumption levels stated in its advertising. Never mind that the same also could be said for almost every other car on the market.
That such discrepancies exist, however, is not wholly the fault of the vehicle's manufacturer. The automakers are just following the testing and reporting rules prescribed for them.
Those rules were initially set out by the U.S. Environmental Protection Agency (EPA) and subsequently adopted by the Canadian government, where they are currently administered by Natural Resources Canada (NRCan).
According to NRCan, the resultant fuel-consumption ratings are intended "to give car buyers comparative information about the fuel consumption of different models based on standard tests."
Note the two key phrases: "comparative information," and "standard tests."
"Comparative information" means the data can be used to compare the performance of one vehicle relative to another. It does not mean that all drivers can expect to achieve that level of fuel consumption with that vehicle in all conditions.
Using the same "standard tests" is what makes the data comparable. It's an "apples-to-apples" comparison.
Where the problem begins is that the standard test procedures are not really indicative of the driving patterns and conditions of most drivers, particularly in Canada.
They were originally based on a typical "Los Angeles" driving cycle, but probably aren't even applicable in that environment any more.
The test currently used to determine Canadian ratings includes two driving cycles, City and Highway, and separate ratings are determined for each.
Both are conducted at an ambient (surrounding air) temperature between 20 and 30 degrees C, with an initial cold start for the city test with the vehicle stabilized at that temperature.
One can see right away that it might not be typical of Canadian conditions for much of the year.
The City test covers 17.8 km at an average speed of 34 km/h, with a maximum speed of 90 km/h, 23 stops, more than five minutes of idling and relatively light acceleration rates (maximum 5.3 km/h/sec).
The Highway test covers about 16.8 km at an average speed of 78 km/h, with a maximum speed of 97 km/h, no stops and similarly light acceleration rates (maximum 5.2 km/h/sec).
Not much like the driving most Canadians do, it seems, which is why the resultant ratings (L/100 km) are adjusted upwards by 10% (city) and 15% (highway) to more accurately reflect real-world results.
As has been proven by journalists in the Automobile Journalists Association of Canada's (AJAC) EcoRun demonstration over the past couple years, those numbers can be achieved in the real world if one drives exceedingly carefully with that objective in mind.
But it's unrealistic to expect people to do so.
Different U.S. standards
To further close the gap between the reported figures and customers' own experience, beginning with the 2008 model year, the EPA adopted new test procedures that added three more cycles to the process.
They address cold starting and operation at a lower temperature (-7 degrees C), hot starting and operation at a higher temperature (+35 degrees C) with air conditioning on, and operation at higher speeds (maximum 129 km/h), with quicker acceleration (maximum 13.6 km/h/sec).
As a result, published figures in the U.S. tend to be less optimistic and closer to real-world experience.
But, for reasons not quite clear, Canada did not change its fuel-consumption testing procedures to match those in the U.S., choosing to stick with the two-cycle test results.
Consequently, our fuel consumption ratings have since been different from those for the same vehicles sold in the U.S. and continue to be further away from what customers can realistically expect.
The scuttlebutt from Ottawa now suggests that an announcement of changes in that situation is imminent and that the disparity between the Canadian and U.S. figures will be remedied in time for the 2015 model year.
If that's the case, based on comparisons between advertised figures for the same vehicles in the two countries, the Canadian ratings are likely to increase by about 15%.
That increase is not likely to bring the advertised figures fully into line with customers' real-world experience – but it will bring them much closer to realistic expectations.