Hi, welcome to the site, Paul.
My '08 also gets bad fuel economy in the winter. I've gotten as low as 27 US mpg, although I average more like 32 US mpg (I live in Canada, so I converted those to US figures). My best tank in the summer was 49.0 US mpg and my worst tank ever was 27.4 US mpg. My average over nearly 2 years from the time I purchased the car until now is 39 US mpg.
A few things you can do to help is do the grille block mod, where you place strips of foam (such as pipe insulation foam cut lengthwise) into the grille slots. Also, if the car is parked outside overnight, install and use an engine block heater, turn it on about 2 hours before you're set to go somewhere.
A few other ideas:
- If it's not too cold and you're sitting at a red light or at a drive thru, turn the
A/C Auto off. That will turn the car's engine off as to not waste fuel. Turn it back on when you're moving again.
- If it's not too cold and your trip is short, don't even turn the heat on. For me though that's going too far

- Combine shorter trips into one longer one. Once the engine is warmed up it's a lot more fuel efficient, even in the colder weather. Start by going to the furthest away stop first so the engine has time to warm up, then make your way back home doing stops along the way (the engine has a chance of retaining some heat at the other stops if it's fully warmed)
I hope that helps!