For the last month the gas mileage on my '90 740 GL Wagon has shrunk from about 27-29 mpg on the highway (which I drive 90% of my gas tank on--no stop lights back and forth to work 20 miles one way) to lately about 21-23 miles per gallon. I have tried to justify this sudden drop as an effect of the cold weather (teens, single digits) here in Illinois for the last 3-4 weeks, though I've never had a car that responds THAT negatively to colder temperatures. But then today the CHECK ENGINE light just went on, and stayed on, so now I think there must be a relationship between these two phenomena. I've spent about 40 minutes looking at the BB's archives to find out what to do when this light comes on, and I've concluded that I need to figure out the 3-digit code and look in a manual for what it means. But before I go ahead and start this process, does anyone have a hunch about what this could be? Anyone have an experience with a sudden loss of mpg? Thanks for any responses. Rick

1990 740 GL 149K