My thoughts on mileage
 

I've owned my 12 eco lariat 4x4 3:73 for 2 weeks now, and yesterday got my first chance to see what kind of mileage it would get on a trip. Most of my mileage up to now has been city streets.....(between stop signs, with a couple of 30 to 60 mile trips mixed in. Was averaging around 16.5. Yesterday however, I took a trip of about 225 miles one way. The first 30 miles are flat, the next 145 are rolling hills, and the last 50 are pretty steep. I averaged 18.8 on the way up, and 18.6 back. I tried to drive about the same speed both ways, and had the cruise set on about 72 for most of the trip. I am pretty pleased especially considering the power this little v6 packs.
Here are my observations: First, I really think this thing does better on fuel in the hills. It seems to gain more going down than it loses going up, as the first part of my trip up, I was getting about 17.5, and as I started into hilly country, it seemed to gradually come up. On the way down, It stayed around 18.8 until I got back to flat land where it dropped to 18.6, and the instantaneous mpg seemed to hover just below the average more than it did above it. Second, I have a hard time figuring out what is affecting the mileage, for instance, sometimes it seems to gain mpgs going up a slight incline and sometimes seems to lose mpgs going down a slight grade. Maybe my internal level meter is just screwed up, I don't know. But I do know the fuel mileage varies widely, so it takes a pretty long trip for it to equal out.
I also love the way the cruise maintains speed. It doesn't matter how steep the hill, the cruise maintains the speed almost exactly up and down. The trans even downshifted going down one hill to keep the speed down.....That's something I've never seen before, and the overall driving experience was very good.
I also like the fact that I just took a 450 mile trip, and it still says 200 miles to empty...... Awsome, even if it is a 36 gallon tank.

I took a long trip over several weeks this summer, and one thing I noticed about cruise control is that it had a tendency to suppress the MPG on relatively steep downhills. Several times, it downshifted fairly hard and drove the RPMs way up as a way to maintain the speed. I eventually got in the habit on long declines to take CC off and just let the truck run with mild braking when needed. The average interval MPGs consistently increased as the truck was in more of a coast than cruise mode.

I found that instant MPG's is such a huge distraction even though I can't keep my eyes off of it. Any change in RPM has an immediate impact on MPG's. I can travel at 35 MPH in the city and get worse MPG's than I would on the freeway at 70.

The instant MPG's has taught me to use less throttle and to be more conservative.

That's pretty cool.

them dont same to get good mpg then 05 4.6 gets 19

My '04 4.6L Expy gets 19+ but with a whopping 232 HP and not enough torque to pull much of anything. It's not only about MPG's but the power it puts out as well.

Unfortunately Ford has yet to solve the riddle on poor towing MPG's. These engines will drink when they are pushed hard.

Not rocket science boys. With forced induction the fuel has to be greatly enriched under high load and high boost. They do that to save the engine from melting down.

10 years back I took my 87 TBird turbo coupe on a trip from SD to Charleston SC. My sister inlaw and family followed along in a Chevy Lumina van. I averaged 28-32mpg for entire trip except the tank going through mountains wher i got 22mpg. (Brother inlaw got his best mpg on that tank) Turbo was under boost all the time.

Towing is similar, you increase weight and drag. Engine works harder.. With a NA engine fuel injectors are usually sized smaller and fuel maps are more conservitive, therefore towing MPG can only get so bad ( based on how much the injecors can flow)..