irregular idling and air filters

Your air filter is one of the most critical items for getting maximum mpg out of your car. If you want to check it just unclip the top of the filter case and remove the filter and hold it up to a strong light and see how much light you can see, if not a lot change it, for about the cost of a tank of gas. 7,000 dusty old YK miles just might have plugged it to the point where it cuts into your mileage. Also short trips and lots of cold starts, winter gas 8L per 100 might be what you get. My wifes 2k4 has climbed to the high 6's with the onset of winter, or what we call winter here on the left coast, and her type of nomal day to day trips, short distance, multiple stop/start, but is way better than most do under the same conditions.

 

I've noticed irregular idling also, but that is when I drive and stop while in B mode. Make sure your wife isn't using B for normal day-to-day driving.

 

just experimenting