Canadian vs. US MPG Ratings

[Flashman]

I had noticed that in Canada the 2008 Smart ForTwo (same engine) is rated at 48city/59highway (imperial gallons). Which is the same as 38city/47highway (u.s. gallons).

I always figured that they simply used a different methodology. But in reading the Canadian government website I learned that they use the "same" methodology as the U.S., a standarized test.

If they are using the same testing methodology, anyone have any ideas why the ratings are so different? Based on most users actual mileage, it seems the Canadian numbers are a lot closer to reality, while the new U.S. rating is lower than average.

[Old smart]

One difference is that in Canada they don't put the car to the test until it has 3,000km (1,860 mi) on the engine. I can't find anywhere where the EPA breaks-in the engine before testing.

[Flashman]

Originally Posted by Old smart

One difference is that in Canada they don't put the car to the test until it has 3,000km (1,860 mi) on the engine. I can't find anywhere where the EPA breaks-in the engine before testing.

Actually it's 6,000km, and they only test with the engine pre-heated. See below:

Testing procedures for vehicle fuel consumption
It would be difficult to drive every model of new vehicle on the road to measure fuel consumption. It would also be almost impossible to consistently duplicate on-road testing results as there are so many variables impacting the vehicle. Instead, a carefully controlled method of testing, including the use of standardized fuels, laboratories and testing equipment, is used to ensure that all vehicles are tested under identical conditions and that the results are consistent and repeatable.

The Federal Test Procedure (FTP) is a standardized laboratory test method used in Canada on new vehicles. Selected prototypes of new vehicles are “run in” for about 6000 kilometres (km) before testing. Vehicles are mounted on a programmable two-wheel laboratory chassis dynamometer. Then a trained driver runs them through simulated city and highway driving cycles. All vehicles, including four-wheel (4X4) and all-wheel drives (AWD), are tested in two-wheel drive mode.

However, tests are adjusted to reflect the increased weight and engine load using 4X4 and AWD systems. Fuel consumption ratings are generated based on test cycles and correction factors that take into account the aerodynamic efficiency, weight, rolling resistance and drive mode of different vehicles and the achievable real-world driving conditions in Canada. Other adjustments are made to reflect the average fuel consumption of vehicle configurations, options and sales mixes sold in Canada.

The FTP is composed of two tests – the city test and the highway test.

Simulated city course
The city test simulates a 12-km, stop-and-go trip with an average speed of 32 km/h and a top speed of 91 km/h. The test runs for 23 minutes and includes 18 stops. About four minutes of test time are spent idling, to represent waiting at traffic lights. The test begins from a cold engine start, which is similar to starting a vehicle after it has been parked overnight during the summer. When the test is completed, the test cycle starts again with a hot engine start, and the first eight minutes of the test are repeated. This simulates restarting a vehicle after it has been

warmed up, driven and then stopped for a short time.

Simulated highway course
The highway test simulates a 16-km trip with an average speed of 77 km/h and a top speed of 97 km/h. The test runs for 13 minutes and does not include any stops. However, the speed varies to simulate different kinds of highway and rural roads. The test begins from a hot engine start.

[Flashman]

Think I found an answer:

CAUTION ON USING U.S. FUEL ECONOMY DATA FOR
COMPARISON PURPOSES

For the model year 2008, the United States has implemented additional adjustment factors and testing procedures than those used for Canada. Consequently, fuel efficiency ratings in Canada and the United States can differ significantly.

Furthermore, U.S. fuel economy ratings are listed in miles per U.S. gallon (the imperial gallon is 20 percent larger than the U.S. gallon) and are averages based on U.S. sales and adjustment factors for each particular model.

Think I'm more impressed with the Canadian testing though, as it is closer to what real-world drivers are seeing.

[saskdiesel]

Originally Posted by Flashman

Think I found an answer:



Think I'm more impressed with the Canadian testing though, as it is closer to what real-world drivers are seeing.

In Canada, many of us prefer the U.S method of testing.
How many people drive 77kmh on the highway?
I think you numbers are closer to the truth. But the diesels sold here did get better economy than then gasser. But they had a bit more than half the power.

[SmartCard]

Originally Posted by Flashman

I had noticed that in Canada the 2008 Smart ForTwo (same engine) is rated at 48city/59highway (imperial gallons). Which is the same as 38city/47highway (u.s. gallons).
Based on most users actual mileage, it seems the Canadian numbers are a lot closer to reality, while the new U.S. rating is lower than average.

I dunno....seems like 38 city/47 highway is a little higher then most of us are averaging.

[rawlus®]

i think the truth lies somewhere in-between. canadian may be "under best circumstances" while US is obviously a low-ball estimate, intentionally conservative.

so canadian estmates are saying "you could get as high as 38/47" while US estimates are saying "you should get at least 33/41"

[Flashman]

I have a baseline. I have two years of data for my 2004 MX-5. Mixture of all styles of driving. It is rated in the new U.S. ratings as 18/21. However, I constantly get 22city/28highway as a 90-day average. On really long drives I can get 29-31 highway.

The canadian estimate for my car is 22/30.... a LOT closer to what I actually get than the U.S. 18/21. I have to really drive like a race car driver to get fuel economy that bad.

[saskdiesel]

Originally Posted by Flashman

I have a baseline. I have two years of data for my 2004 MX-5. Mixture of all styles of driving. It is rated in the new U.S. ratings as 18/21. However, I constantly get 22city/28highway as a 90-day average. On really long drives I can get 29-31 highway.

The canadian estimate for my car is 22/30.... a LOT closer to what I actually get than the U.S. 18/21. I have to really drive like a race car driver to get fuel economy that bad.

But the Canadian gallon (British Imperial) is larger then the US gallon.
One Imperial gallon has 4.54 litres.
The US gallon has 3.75 litres.

[Flashman]

Originally Posted by saskdiesel

But the Canadian gallon (British Imperial) is larger then the US gallon.
One Imperial gallon has 4.54 litres.
The US gallon has 3.75 litres.

Yes, I know. All my quoted numbers are adjusted properly. (multiplied by .8)