It all depends on your driving habits, your area/road types, speed, hard vs soft acceleration, etc. Price of fuel in your area also dictates how much you spend.
Personally, in my '05 V6, i can sometimes eek out 15mpg if I'm very cautious with the go pedal. Generally, I'm between 14.5-15 in town. (This is calculated using the miles driven divided by gallons to fill technique. The MFI readings are more optimistic than a motivational speaker on amphetamines.)
I just filled up this morning. I generally try not to run it down too low, but I ended up filling with 22.27 gallons of 91-proof, which covered 319 miles, for 14.3 mpg. Cost was over $73 @ $3.299 per gallon. If I run the tank down like this, I generally get 8 or 9 days out of it.
(The main reason this was lower than average was some low-range, high RPM romping in the mud on Friday. Since it rained, I had to practice my drifting/donut techniques before I head back home (Ohio) for Christmas.

)
Matt