Fuel economy, v8 -vs- 4cyl
 

Ok, my wife and me are having a little debate about what kind of gas mileage a 5.0 mustang gets.

Can a stock 5.0 get close to or as much gas mileage as a 4 cyl mustang and how close are they?

I usualy get 23-25 mpg on the highway at speeds of 70-75 mph.
what i do is this: i live about 15-20 minutes from highway so i fill-up just before getting on the higway and the car is all warmedup and ready to cruise, i drive 70-75 and have gotten 26 mpg. around town is a diff story, then i think that the smaller engine can get better mileage.

On average, a 5.0 gets about 200 miles to a tank, if you stay out of if. My 2.3 gets about 285-300 miles to a tank, getting on it(Lord knows you have to:()

I've had two 5.0L mustangs and one 2.3L mustang here's what i had (all were 5 speed cars):
my '91 2.3L got 18-22 miles per gallon regularly (100k on engine)
my '84 5.0L LX got 16-19mpg regularly (150k)
my '89 GT gets regularly 17-21mpg (125k)
My GT also has 3.55 gears and a few mods that i would think reduces gas mileage (mileage is the same as when i bought it with only a few small mods).
The power differance easily justifies the purchase of a 5.0L over a 2.3L. I think the main reason i got the mileage i did was because a 2.3L has to work harder to move a 3000+ lb. vehicle so you have to floor it more which makes the engine pretty inefficient if it's trying to run richer for more power all the time. I used to have to wrap it out at full throttle and drop gears just to make it up hills, now i go part throttle in one gear and the torque just pulls it up hills.
i usually get 220-260 miles per tank of gas depending on when i fill up (hardly ever get to the "E" mark, but close) usually i fill up 10.5 to 12.5 gallons.

Both my 5.0's got better fuel economy than both my 2.3's.

88LX 2.3 Hatch A4LD 16-18cty/23-25hwy
88LX 2.3 Hatch A4LD 14-18cty/18-24hwy malfunctioning computer for most it's life. :D
88GT 5.0 Hatch 5spd 18-20cty/26-28hwy
87GT 5.0 Hatch 5spd 19-21cty/27-29hwy

I never get less than 225 miles on a tank. Usually, it's closer to 260 with a couple gallons left.