Hey everyone new to the forum here, I have a 2007 mazda3 in the great white north (Ontario) now this is the second winter that we have owned it and again we have lost about a 100kms on a tank of fuel this works out to around 60miles if anyone is wondering. I do have winter tires on at the moment but I can't see this accounting for all my missing fuel mileage. Any insights?
Thanks guys!

 

It is colder than last year! More Cold = More Fuel.
Make a winter front out of rubber flooring bought from Rona like i did. Put some slits in it (not *****) and tie it down with nylon ties. Cover most of your grille. Leave opening on side where air intake is.
This will allow your engine to warm up quicker. I recently found that i also had to cover the Mazda emblem because it allowed large amounts of cold air and maple keys in to the engine!
Finally it heats up a little quicker.
Try also some good fuel injector cleaner.

 

Here's my updated winter front with all this cold weather. Lot's of salt, crap on front.
It doesn't help that i have a 180 degree thermostat and removed the engine cover either!
But this new set-up is warming up quicker and more heat in heater. Drove it for over 30 minutes without overheating or driveability issues.