Personally, the cold weather is killing me right now. I bought a HCH II a couple of weeks ago in Michigan, and for the first week of 70 degree weather I was getting about 38 mpg on short trips in town and 48-52 mpg on the highway. This past week it's been freezing and snowing here, and I've only been getting about 32 mpg on short trips around town. Hopefully once the weather warms up and I break the car in (there's only about 350 miles on it) I'll keep it in the 40-50mpg range in town. Still, it's pretty frustrating to see the average mpg drop every time I take it out for an errand.