I suppose I should have done this before but it does seem daft to pour petrol down the drain by not driving as economically as I can. Seems to me that if the fuel tank of our Corsa holds about 45 litres of fuel that's going to weigh around 45 kilos, or not far off 100lbs. Given that the heavier the car is the more fuel it will use at any speed it makes good sense to drive with a lighter fuel load.
My plan is to run the tank down until the fuel light comes on and then to put around 25 litres of fuel in instead of filling it up. This compromise will reduce fuel consumption whilst still giving an adequate range for general driving around. 25 litres is 5.5 gallons which at 43mpg will give us a range of about 236 miles, more than adequate for general driving around locally.
If we get snow and ice I'll increase the fuel load to hopefully improve traction but also as a precaution should bad weather cause delays etc.