Start with XtremeRevolution’s http://www.cruzetalk.com/forum/27-fuel-economy/5387-how-get-better-fuel-economy.html
. Next, understand that a seasonal drop of 2-10% in fuel economy is very common in the winter. Below I have listed several reasons why and methods to reduce their impact.
1. Winter Gasoline, at least in the US, has about 2% fewer BTU than summer gasoline. There is nothing the average driver you can do about this. This also sets the lower level of reduced fuel economy at 2%.
2. Motor oil is thicker in low temperatures. You can work around by keeping your car in a heated garage, using an oil pan or engine block heater. Short trips in the winter are really hit hard by this additional friction within the engine.
3. Warming up the car by idling before driving. This isn’t required for the Cruze and wastes fuel. While the car idles, it’s getting zero MPG. You can start driving as soon as your RPMs stabilize after starting the car. You don’t have to wait until the RPMs drop to the 700-800 RPM idle, just keep the engine speed down. I keep my engine speed below 1500 RPM (turbo spool up start) for at least the first minute of driving.
4. Clear frost, ice, and snow off your car before starting the car (see #3). All three reduce visibility unless cleared and scraped from all
windows. Brush off snow buildup from the hood, roof, and trunk of your car. Snow buildup decreases fuel economy by adding both weight (low speed) and air drag (high speed) to the car. In some jurisdictions (New Hampshire is an example), you are required by law to remove snow from car’s hood, roof, and trunk before driving. Don’t forget to clear your headlights, fog lights, and taillights. Remove ice buildup from the wheel wells as well. Be careful when scraping around the wiper blades as you can damage the rubber inserts with your scraper. I know, I've damaged mine on past vehicles. Clear any ice buildup from the wiper blades, arms, and pivot points.
5. Loss of Daylight Savings Time. As strange as this sounds, westbound afternoon congestion hours actually start an hour earlier by the clock in the winter than they do during the summer. For example, if your afternoon congestion starts at 4 PM in the summer it will start as early as 3 PM in the winter, even on a dry road. This is because the sun is that much lower and people start slowing down up to an hour earlier, which leads to earlier congestion. You can mitigate this by finding a different westbound route home. For example, I work in Aurora, CO (southeast of Denver) and have to get to C-470 and Santa Fe on the southwest side of Denver. In the summer I can use C-470 with no problems because the sun is high enough to not impact driver visibility. C-470 snakes north and south of due west, which means in the winter the sun is low enough at 3 PM that there are parts of C-470 that are driving directly into the sun. Very few drivers keep their windshields clean on the inside so they end up slowing down at 3 PM instead of 4 PM. Find an alternate route. I use Bellevue in the winter, which even with stoplights provides a much more consistent speed (improved MPG) than C-470. At no point do I ever drive directly into the sun.
6. Snow and Slush on the roads adds significant friction that doesn’t exist on a dry road. Water also adds friction, but not as much. You can reduce this friction by staying in the tracks that people in front of you have created. This does, however, reduce your stopping ability. The friction from snow and slush helps you slow down faster without skidding.
7. Plan your trips to for the middle part of the day, which tends to be the warmest. Also, plan your route to use predominately right turns and drive far enough to fully warm up the engine before your first stop. A warm engine gets better fuel economy and right turns require less idling.
8. Slow down. Not only does this improve fuel economy but it also gives you more time to react to other drivers and obstacles on the road.
9. Consider covering the lower grill of your Cruze. The ECO trims do this automatically when it’s cold by closing the louvers even at low speed.
10. Practice mild hyper-miling techniques year round. In the winter you want to be smooth to improve both vehicle control and fuel economy. This must be muscle memory for it to work.
11. During the warmest part of the day and after the car has been driven enough to warm up the tires, boost your tire pressure as high as you are comfortable but not over max sidewall. This will keep the tires from underinflating overnight. Use your TPMS to ensure all four tires are within a pound of each other to improve handling.
12. Winter air is denser, which has both negative impacts at highway speeds and positive impacts during low speed acceleration by adding additional air pressure for the engine to work with. About the only thing most of us can do with this is enjoy the cold and take up a winter sport of some sort.
13. Don't heat the cabin until the car's temperature needle is to the 1st quarter mark. You can get heat sooner, but at the expense of fuel economy. Remember, a warm engine is more efficient. If you need to run the defroster, select recirculate to avoid pulling in more cold air. Many cars select recirculate automatically when using the defroster but I don't know if the Cruze is one of them.
For a rundown from CleanMPG.com, try A Hybrid Owner’s winter survival guide - CleanMPG Forums
Feel free to add to this list and discuss/shoot down my observations gleaned from over 25 years of tracking my MPG in multiple vehicles. Also, I'd like to thank various members of CruzeTalk who gave me some of these ideas that I hadn't previously figured out.