Cars: Where do vehicle fuel ratings come from?

(NC) — An informed consumer is an empowered consumer especially when it comes to understanding the fuel efficiency of the vehicles we drive.

Vehicle manufacturers test their own vehicles using standardized testing procedures. The information from these tests is then used to generate fuel consumption data. Environment Canada collects this data from manufacturers and Natural Resources Canada uses it and other information to publish its annual Fuel Consumption Guide. These same ratings appear on EnerGuide labels and are affixed to all new light-duty vehicles at the point-of-sale.

Since it would be almost impossible to drive every new vehicle model or duplicate on-road testing due to fuel consumption variables that can affect a vehicle's performance, a controlled laboratory testing method is followed. This ensures consistency whereby all vehicles are tested under identical conditions and where the results are consistent and repeatable.

Fuel consumption ratings are based on two test cycles: city tests, which simulate urban driving in stop-and-go traffic and highway tests, which simulate a mixture of open highway and rural road driving, typical of longer trips.

Fuel consumption ratings are meant to allow consumers to compare vehicles while being assured that the same testing procedures are being used by all manufacturers. While in many cases it is possible for a driver to meet or exceed a particular vehicle's fuel ratings, fuel consumption ratings are based on a specific testing protocol.

In short, your over the road fuel consumption can be affected by:

Your driving style and behaviour;

Vehicle acceleration, braking and driving speed;

Overall age and condition of your vehicle;

Temperature, weather, traffic and road conditions;

Drive systems and powered accessories such as air conditioning or heated seats and mirrors;

In addition, small variations in vehicle manufacturing will cause fuel consumption differences in the same make and model and some vehicles do not attain optimal fuel consumption until a break-in period of 6,000 to 10,000 km.

You can download a Fuel Consumption Guide at


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