I've had my Highlander since July, and have been very satisifed overall. I live in Chicago and do mainly "city" driving. I was getting 27-29 mpg until the weather turned much colder, and the gas stations changed to the winter mix gasoline. Now I'm only getting 20-23mpg.

It appears that the hybrid system works completely differently in the cold weather, even after the engine warms up. It doesn't want to let you use only the electric battery - whether moving from a stop, or at cruising speed.

Also, when it is VERY cold (like less than 15 degrees), and the city traffic is really bad with a lot of standstill time, it seems like the engine NEVER warms up because it keeps shutting itself off when the car is standing still.

Is anyone else having this experience?