Since my car was new, I was keeping track of tank mileage on trip odometer A, and lifetime mileage on odometer B. In other words, I never reset B. At over 11,000 miles, it was at 34.4 mpg. I recently checked the reading at my last fill-up: Lifetime mpg 0.8. Something's obviously not right with that... Even if it had been inadvertently reset with the reset button, it would have read somewhere around 30 mpg, and probably higher, corresponding to the mpg since the reset. I left it alone, and checked it again at the next fill-up: 1.8 mpg. So it's slowly creeping back up.

It appears that what happened is that the total miles traveled reset itself, but the total gallons used continues to be tracked and didn't reset. This happened at some point over 11,000 miles. So the trip computer now thinks I've used hundreds of gallons of fuel and traveled just a few hundred miles, and therefore reports 1 or 2 mpg, lifetime.

Anyone else experience this kind of reset? Maybe the trip computer can only handle a reading no higher than 11,000 and some miles, then goes back to zero? It never happened on my Civic, however. I can live with it, of course.