I find liters/100km to be an extreemly awkward measure. If you have to exist with metric why not km/liter.
To convert to good old MPG(Canadian) divide 283 by the liters/100km.
To convert to good old MPG(US) divide 236 by liters/100km. The US gallon being .8345xCangallon.
I think that the US milage ratings have fairly recently been modified to more accurately reflect on the road experience. It seems that no one was getting the Monroney Sticker posted ratings before. I have not heard that the Canadian rating system has been similarly modified so conversion between the two Monroney Stickers (US/Canadian) may not be possible except by multiplying the Canadian rating by about .8 or so.
If in fact the Canadian rating is still the unchanged, I think a strong tailwind would have to be involved to achieve results close to the rating. Also elevation of departure and arrival is important. If you know that your trip is significantly down hill overall, fill up with gas. The extra dissipation of potential energy will help.The reverse of this applies on the return trip. (use half fills if convenient)
The only measure of gas consumption is,fill up to fill up, versus distance travelled. Even here consistancy in pumping pad slope can have a significant affect. A pad sloping down away from the pump will allow for more gas to be pumped in before the click. (How accurate pump clicks are is unknown from pump to pump)
All in all, the sticker rating is only a measure of gas consumption from car to car. Obtained under constant conditions to be a guide only for consumers. Accounting for driving habits is not possible.
