Am I getting "too good" fuel mileage? Something wrong with my car?

Yep that sure is the case, especially during low speed driving around 40MPH and under.

With freeway driving when the engine is running most of the time then the Prius is not all that much different any similar sized car in terms of engine heat production. Probably a little bit less due to the more efficient atkinson cycle engine, but at low speed driving when the engine's only running half the time then there's a big difference.

When I change the oil in my Madza (2005 Mazda2/Demio) I take it for a short drive around some local roads just to warm it up enough to drain more easily. After the short drive the sump and oil are warm enough to burn your hands. The first time I had to change the oil in the Prius I took it on the exact same "warm up" route that I always use on the Mazda and was astonished to find that the oil and sump were only lukewarm.

 

My 09' touring with 52(maybe 55k i forget) sometimes has reported 62mpg. I compared the fill up to what the screen said and i was above by 10mpg. I was a bit skeptic though. Since it doesn't seem like you're allowed to use your entire gas tank, i thought possibly it had shrunk a little bit, thus making it seem like my mpg went up. My Car typically says 49-52mpg avg during warmer times. In the winter its usually 40-45mpg avg. Doing the same driving.

At those times i was driving 54ish miles daily. Mostly highway speeds between 65-75mph. Then back road to work doing stop n go. But now i'm off on disability while having complications from surgery, and the car does 98% city right now. lol

I could believe under the right circumstances getting 60+, but with the wonky gas tanks its hard for me to believe.