[onewhippedpuppy]

Originally Posted by jyl

They do provide some information about their fuel economy test procedures. Car Testing | Auto Test Center - Consumer Reports

My recollection of my time driving 4 cyl turbo cars was that they got good mileage if you dribbled along at low rpm off boost, but if you were on boost a lot the mileage was a lot worse. Maybe the CU tests involve more acceleration than the EPA tests. Which is more realistic? I don't know but I seldom hear anyone praising the EPA tests for realistically simulating real-world driving. In fact, when talking about hybrid mpg (e.g. Prius), people here quickly discount the EPA tested mileage.

I didn't see this, in my opinion it still leaves a lot of room for error.


From the CR site:
Fuel economy

We perform our own fuel-economy tests, independent of the government's often-quoted EPA figures and the manufacturers' claims. Using a precise fuel-flow measuring device spliced into the fuel line, we run three separate circuits. One is on a public highway at a steady 65 mph. That circuit is run in both directions to counteract any wind effect. A second is a stop-and-go simulated city-driving test done at our track. The third is a 150-mile "one-day trip" using several drivers taking turns around a 30-mile loop of public roads that include a highway section, secondary roads, and rural byways. CR's overall fuel-economy numbers are derived from those three fuel consumption tests


Public highway at 65 MPH - adjusted for temperature, seasonal fuel blend?
Stop and go simulated city test - how do you maintain consistency in acceleration, braking, etc?
Day trip - how do you maintain consistency for acceleration, braking, etc? How do you adjust for differing traffic patterns, weather, fuel blend?