New POSSIBLE "fix" to try for those suffering from obscenely low gas mileage. (BELOW 20 overall for us).
The dealer hooked up our car for a diagnostic and sent us away with "no codes= no problem", BUT the car has been getting significantly better mileage since. Including a "calibrated" mixed freeway-city errand running.
Time will tell if this is a temporary "glitch" or if maybe hooking it up cleared some bad setting or something.
Car runs smoother and no hard starts since. Its only been a couple days. Time will tell, but we have some hope now.
Sooooo..... maybe try getting the dealer to run a diagnostic? MAYBE try shutting down the computer (unplugging the battery) and hooking it back up again to reset it. Just a wild guess, but might be worth a shot. (no warranties expressed or implied)