[AutoItKing]

Yah for real with these threads already... Use your "odometer" and see what it say's when you fill up. Then drive until its empty, take that number, subtract it from the original, then divide by the gallons you put in the tank.

Since people don't seem to understand this, here's an example: Say you have 100 miles on the odometer. You run out of gas and it says 400. You fill up 13 gallons. 400-100 = 300 miles. 300 / 13 = 23 mpg.

I literally learned this in like elementary school. Why are so many people on this forum having such difficulty with basic math...

Because the average American's IQ is about 20.

 

[AutoItKing]

What I think happened here is that when you disconnected your battery you also reset the ECU, and our ECU is a smart one that learns your driving habits. When you reset it, it forgot how you drive and now has to relearn. So it thinks you're a more conservative driver.
But don't rely on the trip computer to tell you what your mileage is, use a piece of paper and a calculator. Much more accurate.

 

[AutoItKing]

...Must be an echo in here...

Haha whoops, missed that entirely