Hey I have a 99 Dakota 3.9l V6, and I have questions on how be my tank really is and if my gas gauge is properly working. I can fill it up and it will stop a tick past 3/4 and full. But I'm getting 19 to 23.4mpg(87 octane) using the 5spd Manuel transmission without 1st gear having synchronizing issues piping out of gear 90% of the one in the time. When the gas light comes on at 1/4 of a tank left, I can still drive it WELL below the mark. So what do y'all think?? And it has 245/35ZR20's all the way around.

 

Part # on the bottom of the tank will tell you how big the tank is, just look it up in parts. Easiest way, already went through it replacing fuel pump.