Now that I have had my '98 for two full years I can say that fuel economy always suffers in the cold weather. Check the air and fuel filters but don't be surprised if in spring you start to see economy closer to 30 around town and 34 on the highway. I routinely see fluctuations on the order of 10-15% on MPG and it is always lower in the cold...probably a combination of winter blend fuel and lower effeciency of the engines in the cold weather.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz