I am not pulling your leg but I have been having a pleasant phenomenon happing with my 2000 ML320 - the gas mileage has been increasing substantially the past 3-4 months. We had been getting around 21 mpg on a trip. Today I just completed an 1116 mile trip where I have averaged 23.7, with as high as 25.8 on one 183 mile leg of highway driving. The driving environment was a range from gravel roads, township roads, county roads, state highways, multilane non-freeway, freeway and city. It was as about a complete mixture as possible. My speeds were at or above the speed limit and I haven't changed my driving habits, and the performance hasn't been affected. I use the cruise control whenever reasonable. The odometer is correct, as I was on a route with mostly known distances and the segment mileages were correct. I have new tires but the same model as the old ones. I used the AC about 50% of the time. The trip was a round-robin trip so altitude changes were not a factor, and didn't vary more than 100 feet anyway. The temperature was 60-75 degrees with rain about 50% of the time, and drove throughout various times of the day from 8 AM through 1 AM. I bought gas at a variety of stations in various towns; Conoco, Holiday, Exxon and Kwik Trip, so the brand of gas shouldn't be a factor. One fill was after about three-fourths tank of gravel roads.

The only changes lately have been with the 320's CEL. About the end of March it came on intermittently and was on about 60% of the time. On this trip it was on about the same amount. I had had the 320 in for a free inspection at a customer appreciation event and the tech's made a note that the airflow sensor needed replacement. The vehicle is due for a "B" service.

I have no complaints about the increased gas mileage, of course, but am curious as to why it is happening. The overall average mpg has been increasing since the vehicle was new but the past 3-4 months it has jumped. Any ideas?

Jim W.