Mine was up to 1.9 mpg today, and I gave up on it fixing itself, and reset it. It immediately started acting properly, and over the ~15 miles to home, it ended up at an average 39 mpg. So it's currently acting properly, after the intentional reset.

It looks like the 11K+ mile partial reset was unique to my car. I'd guess it was a one-time glitch, but who knows.

Actually, I'd like to have 3 trip meters. I'd use one for tank to tank mpg, one for lifetime, and the third for playing with on various driving segments. Maybe now that I've lost the lifetime figure, I'll starting using Trip B that way.