Thats crazy! Something is going on with your cars if you aren't getting the "milage." I can push my 6cyl to 896 km which works to about 13.8km/L. Something has got to be going on. You guys using cruise control? How fast are you driving? The only thing that I can think of is that if you are going high speed you have your rpms elevated for longer...when Im cruising at 70mph (112kph) I am at 2000rpm.

 

Maybe its canadian gas that sucks!

 

I have an 02' EX 2.3L. During the first 500 miles, my gas mileage was running about 19mpg (I'm not sure what the metric conversion is). This increased dramatically. At 10,000 miles, the car now averages 30 mpg.