Smoo, it might be your car is running rich. Check you temps and lambda sensor both can cause excessive fuel consumption, you might need a new thermostat or sensor. For the record I rarely get more than 250 from a tank, is your car standard?
But back to the proper post, there is a world of difference between a Ford 2.5 v6 and a coop turbo, you need to get out and drive one and see for yourself, but its like comparing your old v6 with a standard 1.8 Mondeo.