Does anybody else's mpg drop when it gets cold?
 

First winter with my HHR and I have been getting 33-37 mpg all summer. Now it's stuck on 32.5 mpg ever since it got cold. Does anyone else experience this? A friend of mine says his Nissan does the same thing in the winter.

OMG yes! It's not just an HHR thing, but the DIC msure makes it more obvious. I have lost about 3mpg.:(

It's unavoidable, in any car. The colder, therefore denser air requires more fuel to maintain correct air-fuel ratios.

On turbo cars, this effect can also be exacerbated by the fact that the turbo will boost harder, sooner, thus using more fuel.

A more subtle aspect is that the car itself becomes harder to "push around" in cold weather. This is a twofold effect:

1. Aerodynamic drag increases with the denser air.
2. Wheel Bearing and transmission assemblies, as well as drive axles, induce more parasitic drag when cold. In many cases, save for trips of an hour or more, some of these parts never even get to optimal operating temperature in very cold weather.

My mechanic told me they add something to the fuel in winter to keep it dry and that knocks a few percent off your mileage also.

Last year it happened to my truck in 1 tankfull even though it had been cold for weeks. ---> about 3.5MPG

Winter fuel blends have a negative effect on fuel economy. Be happy that you are getting 32 mpg though because I'm lucky to get 21 mpg right now during my winter drives.

In the cold winters, my mileage would drop dramatically. More time ideling and getting the car up to temperature for "proper" engine running. Also I was driving in slush and snow, slow and go. That was why I moved south. I haven't had the HHR into the snow belt in the winter in about three years..

One big issue is a winter gas blend of 10% ethanol in most states at this time of year. It will drop your MPGs 2 to 3 miles. One reason I stopped using 85% ethanol in my 09...

It simply takes longer for an engine to reach operating temperature in colder weather so the engine spends more time in richer fuel modes.Toss in the other factors(blended gas,increased driveline friction,etc.) and there's your loss of mileage.

Mine's gone up from 19 to 23 since July (100% city driving). But, my hunch is that's entirely due to me not idling with the A/C on while eating lunch.

My remote starter on cold mornings has a lot to do with my decrease.