It's not the most scientific but using the old gallons divided by miles driven method I seem to be only getting about 21-22 mpg. I don't know if it would contribute to the problem but I've had very very bad glow plugs in the car until this week when I changed them. As my temp runs well below the mid point unless I'm PUSHING it, it's been suggested that perhaps the thermostat is stuck open and not allowing the car to get up to a temp that will facilitate full burn. But otherwise the car seems to run REALLY well, strong pull, not too much smoke. I have correct sized tires that are up to pressure. I guess it could be anything but any other big suspect reasons for bad fuel economy?