Traffic must be a real bear. Might also be the gasoline, as it could be different depending on govermental regulations and such. The winter mix we use in the states contributes (in part) to the reduced fuel economy during colder months. The gas mix where you are could be of a much different variety.

I think, however, that you are basically just putting up with some rugged traffic.

Plugs, cap, rotor, wires done recently? Check tire pressure, any roof rack? tiny little things could maybe squeeze another mile or two per gallon out.

Good luck to you.

BB