I have read a little about how the pumps don't pump correctly unless they are calibrated frequently. I believe I read that hear.

"Not sure how the camry works but the HCHII displays an mpg that is consistently is 1-3 mpg below the actual."

That's while I feel that the numbers that the database is putting out are skewed slightly. I don't know how much but I am hoping to get an idea with some analysis that I am doing.