Q: I own a brand-new 2008 Chevy Trailblazer (2,000 miles) with a six-cylinder engine and I'm only getting about 15 mpg with mostly country driving. I asked the technician and he, said that Chevy Trailblazers don't get good gas mileage. I used to own a '91 GMC pickup that had over 175,000 miles on the odometer, and it was getting better than 20 mpg. You mean to tell me that almost 20 years later I shouldn't be getting better fuel economy. What can I do to get better mileage than the 15 mpg I'm getting now? -- H.W., St. John, IN

A: H.W., I looked up your Trailblazer on www.fueleconomy.gov. Your Trailblazer is rated at 14/20 mpg with a combined 16 mpg. It's important to note that those ratings are under ideal conditions. It's also important to note that vehicles don't get as good fuel mileage in cold weather. That's because the fuel is blended differently and the colder an engine is, the more fuel it consumes. Another factor affected by cold weather is a vehicle's rolling resistance. The rolling resistance is much greater when a vehicle is cold. Because of what I just mentioned, and the fact that motorists likely allow their engines to idle longer in cold weather, I don't recommend motorists to check fuel economy during the winter months. They'll likely be disappointed. You should notice an improvement in the fuel mileage once the weather warms up. SUVs aren't known for delivering good fuel economy. If the return of warm weather doesn't bring you the kind of fuel economy you're trying to achieve, maybe you need to look at more fuel efficient types of vehicles.

Q: I own a 2002 Honda Accord EX 4-cylinder with 35,500 miles on the odometer. The car is maintained above and beyond the manufacturer's requirements. Twice a year, I use a premium fuel injection cleaner. Recently, new tires, brakes, and a battery were installed. I used to average 23 - 24 mpg driving in the city. Last fall, a new air filter was installed. I now average 19 mpg driving in the city. What could cause this drop in mileage? -- R.C., Villa Park

A: R.C., there could be something wrong, but first I have a question. Did you replace the tires with the exact same ones? If not, were the replacement tires a different brand, different type, or different size? If the tires are slightly larger, your speedometer and odometer will be off on the low side. That means, you'll accumulate less miles on the odometer than you're actually travelling. That could account for the mpg being lower. If the tires are the same type and size, have a technician plug in a scan tool and check the fuel trim numbers for LTFT (Long Term Fuel Trim) and STFT (Short Term Fuel Trim). They both should be close to zero with a maximum of +5 to -5. Plus means the engine is running lean and the engine control computer is adding fuel to the base mixture. Minus means the engine is running rich and the engine control computer is subtracting fuel from the base mixture. As long as both LTFT and STFT are no greater than +5 and no lower than -5, the engine control system is operating properly. Other items that could cause low fuel mileage are low tire pressures, wheel misalignment, unnecessary heavy items in trunk. Also, make sure that you haven't accidentally turned the overdrive off or are using "Drive" instead of "Overdrive."