My new (to me!) 1992 940 gl (non turbo)runs highway miles almost exclusively. It's practically a 45 mile non-stop country jaunt to work every day. When I drove the car home after buying it, I drove 500 miles (mostly non-stop highway also)and experienced about 28 mpg having the cruise control set at apx 72 mph most of the way. I thought I'd take it a little more leisurely driving to and from work, so I've been setting the cruise at 60-65, hoping to improve on the gas mileage. I thought the lower speed would net better mpg, but I've been getting closer to 25 mpg. Are these cars more fuel efficient at higher speeds? That's what my initial impression is. Also, I'll probably be switching to synthetic oil in the next week or so. My experience with other vehicles leads me to believe that will contribute to somewhat better mpg. Thanks!

Steve