Well there is hope. Got a running start on a new tank. Filled up with a warmed up car, went about 15 kms. Then another 60 kms today from a cold start. I'm sure by the end of the tank it'll have climbed a lot, but at least I don't think there's a mechanical problem, just driving conditions. This is with 15" X-ice, secondary highway driving, fairly level terrain, 2~4C ambient temp, 80 kmh max. It was dancing between 3.7~3.8, translates to 62~63 mpg US. Displayed of course, so maybe 7.5 % less in reality.