2008 4cyl 2WD Escape. Sudden drastic change in fuel economy - no engine light. Runs fine. Went from 9Litres per /100km to 14. What might it be?

You need to have a scanner hooked up to it first to make sure there are no previous codes in the system.....it is possible to have a code stored but no light on, depending on how intermittent the issue is. Not just pulling codes though, but checking sensor data and actually driving and logging it if the shop is capable of doing so. A good technician would be able to look through the output of the sensors and isolate a problem in one of them, if one exists. For example a faulty oxygen sensor or a Mass Air meter that is reading incorrectly. There's many potential culprits and without further testing, it could be anything from just needing a basic tuneup, to needing Oxygen sensors, a MAF, or some other problem entirely. ANY additional info you can provide is helpful in dealing with driveability problems...so if it seems a little slow lately, has an odd smell to the exhaust...ANYTHING that it was not doing prior, no matter how much you think it may not matter, could potentially be useful so don't be shy.

Thanks for the information! I have an appt. booked for next week but I didn't want to chase a vague problem as that could get unnecessarily pricey. I did notice a louder sound (more than normal as I have never found it to be "quiet" ) coming from the exhaust portion of the car, noticeable when I start up and rpms are high.

Make sure you tell them that. If you have an exhaust leak before the oxygen sensors that the ECU utilizes for mixture control, fresh air going through the sensors with the exhaust will cause them to read false lean, which will in turn trigger the computer to adjust the fuel trims and add fuel and drop your economy. That might just be your problem right there.

Cool. Thanks so much. I am not smelling anything unusual but it probably doesn't have to be "big" to be a problem. You are a great help!

Check to see if your OD is working correctly in some cases if the OD (over drive) gear is not working this will make the engine rev higher (sound louder as you mentioned) and will use more fuel, mostly highway driving but will overall effect gas mileage if OD is not working, just a quick and easy check.