Making the US engines less fuel efficient?
Here's a conundrum for you. Why do identical cars from identical manufacturers get lower gas mileages in America? Given the difference in a US gallon and a UK gallon, (a factor of 1.2), gallon for gallon you'll go much further in the European version of the car. Here's two examples showing the city / highway / combined mpg values. For the UK models I've put the imperial mpg first and the equivalent US mpg in brackets. These are for identical spec cars - same weight, same engine, same trim level - everything.
Honda CR-V 2.0 manual
UK 27.2 / 42.2 / 35 (22.6 / 35.1 / 29.1)
US 20/27/23
Honda Civic 1.8 5dr manual
UK : 33.6/51.4/42.8 (28 / 42.8 / 35.6)
US : 26/34/29
Honda CR-V 2.0 manual
UK 27.2 / 42.2 / 35 (22.6 / 35.1 / 29.1)
US 20/27/23
Honda Civic 1.8 5dr manual
UK : 33.6/51.4/42.8 (28 / 42.8 / 35.6)
US : 26/34/29
Comments
Also the type of oil and viscosity if it's different might contribute.
Don't know if the ECU's are programmed differently for different emissions laws in different countries.
I don't know what they do in the US, but here in Euroland, the tests are broadly:
Urban = cold engine, accelerations, steady speeds, decelerations, average speed 12mph, distance 2.5 miles
Extra-Urban = warm engine, accel, steady (50%), decel, max spd 75mph, avg spd 39mph, distance 4.3 miles.
It's possible that the US tests are even less representative of real driving than European ones.