I have seen plenty of 5.4s get that good of mileage, some actually better, up into the 18-18.5 mpg range. I never cared about Hemis, so I don't know what they get.

 

The epa rates mileage. But not on the road. They do so with clever dyno loading and such. It is not always one hundred percent accurate. As such the hemi with the 5 speed auto in a half ton 2x is rated at 14-18mpg. The chevy with the 6.0, prolly the closest for hp and torque, half ton 2x w/ the 4 speed auto is rated at 14-18. The same offering for ford with the 5.4 is rated at 15-19. So in this instance ford has the best and dodge and chevy are tied. As rated by the epa. But if you compare the chevy 5.3 to the ford 5.4 they are tied.

My momma always said. You pay for hp at the pump.

Like the epa? I wonder why the discrepency between the epas results and your dads companies. Different trucks?
http://www.fueleconomy.gov/feg/feg2000.htm

 

Yes it is the EPA. The numbers get adjusted according to other factors such as atmosphere, size of vehicle, weight, and aerodynamics. The mpg figures you have are EPA's rough estimates. The ones I have are true figures--keep in mind they are all averages--meaning some were higher and better than others, just the majority were around the numbers we had.

 

So then they don't advertise it, and you have to request it, right? I guess that makes sense. Thanks for clarifying that...
STU

 

So, in essence, a reg cab w/ no load (besides a large driver ) and some arodynamic upgrades, like bed topper etc, with the 4.6 should really get a real world milage advantage overthe same truck w/ the 5.4? I would like to have 300 under my right foot, but dont really want to pay for it when I'm stuck in traffic all day. Cant use what "the man" wont let you. Besides, I think that the 4.6 should be pretty darn good in that truck. Isnt the engine related to the GT?

 

The 04 GT Mustang currently uses a 4.6L (281cid) two valve per cylinder motor. That motor is rated at about 265 HP. The main difference between it and a truck 4.6 is the cams, intake manifold, and the exaust system. The 05 GT Mustang will use a 300HP/320 ft-lb, 281, with the same three valve per cylinder heads, and the same cams as the 04 F150 5.4 liter. The new GT motor will be all aluminum too. So the 05 GT will have a 4.6 liter motor maybe more in common with the 5.4 truck motor, at least the top end, than the truck 4.6L. Of course the displacement of both 4.6 liter motors will be the same.

While the 2 valve truck 4.6 isn't a big time power producer like the 3 valve 5.4, it has enough tourqe for basic light duty truck work, in my opinion. Normally, the smaller motor should get better fuel milege, but there are so many variables to fuel milege that it's impossible to predict. Were you must work the truck relatively hard, the smaller motor may not get better milege. This is because it has to work harder to get the job done, while the more powerful motor handles the work easier, using less gas pedal.

On the other hand, high power motors can get good fuel economy depending on how they are used, and how you drive, and how the vehicle is geared, how much it weighs, it's aerodynamics, the rolling resistance of it's wheels and tires ...ect... For example, my 5.0 Mustang, at 350 HP and 3.55 rear gears, and 3200 lbs, gets 25 mpg on the highway, at 80+ mph. I rented a V6 mustang on recent trip that only got 21 mpg at 65-70 mph. My sister's 4x4 01 F150 (2 valve 5.4 and automatic) gets 14-15mpg no matter what. The 97 Cummins diesel-1 ton 4x4, gets 20 mpg empty, but about 14 towing a gooseneck horse trailer. My brothers 03 Dodge Cummins 35000 got 14mpg, no matter what. So who knows?

 

So why did the epa list it as 14-18?

 

Reread what I said--they use more factors than just the numbers. Aerodynamic friction, driveline ineffieciencies, and other similar type categories have to be considered, which will change the final number by a mile or 2. They do, and when the numbers come out, the numbers you got is what you have.

 

The epa would not use this same method? The epa's numbers are the ones you see on the window sticker. I always assumed that they were thorough. I am truly curious as to why the discrepency.

 

Did you ever read the fine print on the EPA numbers? Down in the left corner of the sticker it points out that the 14 and 18 are actually averages. The 14 comes from a range of MPG from 11 to 17 MPG while the 18 comes from the average of 15 to 21 MPG. What will your engine make? Well that is a little more difficult to predict. If you got a big foot and enjoy using it, you are going to pay. WHat are your driving conditions like? Do you drive up and down hills all day long? Do you run on flat pavement at speed all day long? Drive a little more moderately and either the 4.6 or 5.4 should reward you with low to mid teens mileage numbers for city and mid to upper teens mileage numbers for the highway.(If anyone actually cracks 20 with a 5.4 I'd love to here from you!) In the end it really doesn't make a whole heck of a lot of difference. I don't think any of us bought these rigs because of their stellar fuel efficiency. If that were true we would all be in a Honda Civic thread somewhere. LOL

 

EXACTLY my point!!!!