Here's my .02
I'm going to comment on several of the things that have been mentioned here. I found this thread by doing a search for comments on the Ford 3. 5L Ecoboost engine. I, too, saw the hype on the ford site, and was impressed. I'm not one to just jump up and go buy one today, I've got to get more research and objectionable thoughts/facts on the subject. The Ford site could be nothing more than hype and propaganda. Maybe next year or the year after I'll own one. For the first time in 13 years I went and looked at a Ford truck, an F-150, not a Superduty. I was looking for a drive-around truck because I can't drive my big dually everyday. Too big and bad on fuel. I miss my '01. I looked at a 2010 F-150 Lariat loaded with everything I want and a 5. 4L /6-speed auto. Nice truck, but the dealer wasn't as excited as I thought he would of offloading their leftover '10's.
Gas vs diesel. When I bought my first diesel in 1999, diesel was a buck o-nine a gall-e-on. The argument was diesels were more fuel efficient, had more power (mostly torque, and an inline 6 has that power where you need it) could pull more, would last longer than a gas motor, and diesel was cheaper than gas. Lots of things have changed since then. There has been a significant shift. Diesel costs more than premium, even though it costs WAY, WAY less to get diesel to you favorite pump station than gasoline. But, we've let the oil companies do what they want, and we're paying for it.
Diesels don't get better mileage anymore, or at least not by much. When towing, they get a little better than a gas burner pulling the same load. So that's not a huge advantage anymore. When I got mine, it was my daily driver and it got better mileage than a gas burner. I could get a smaller vehicle, but I couldn't afford two vehicles. So I needed one to do it all, pull the fiver, drive to work, haul the wife and kids, go get lumber, etc. If I got a gas burner, it would be a small block for mileage, OR a big block for towing. Well, the diesel did both. It came with a bigger price tag up front, but there were other benefits, and that was pulling power and longevity. If you pull 15,000 lbs, and do it often, a gas motor will wear out sooner than a diesel.
Power, the new gassers will pull a trailer, but what has been said is true, the RPMs will be up there, and it's not going to pull HEAVY trailers very well. The diesel is still the champ, but if you don't have a need to pull more than 7k, you don't NEED a diesel.
Longevity. Yes, gassers will last more than 100k, but not if worked hard. Those of you that say you pulled a trailer, and you got over 100k on your engine, you haven't pulled a HEAVY trailer, very much, very far. A small percentage of the 100k was actually pulling a trailer, otherwise you'd have a motor without much power anymore and/or blowing smoke. It just won't do as much as a diesel for as long.
Mileage in the hills vs in the mountains. When I drive my wife's Magnum around FL and TX I get 22 mpg on the road. It's the R/T with the 5. 7 Hemi. When I go to Utah, I get 22 until I get to the mountains of Utah. That mileage goes up to 26+ mpg, that's no joke, and hand calculated all the way. My diesel, same thing. My '04 would get 12-13 on the way there, until I fill up in Gallup NM and drive the rest of the way to Provo, UT, I'll get 14-15 towing or hauling the truck camper. Yes you're using more fuel to climb the mountain (duh) but you're making fuel on the down-side. And driving around in UT as opposed to in TX or FL, my city mileage is also higher. Less power, but less air and the computer is mixing the fuel/air, and it's burning less fuel.
As far as small block vs big-block, a 4. 8L vs 6. 2 L... the 4. 8 liter works harder to pull a 5k load, and a 6. 2L isn't working that hard, and after a certain point, it'll get better mileage than the 4. 8L that's working it's tail off. Even empty mileage isn't that great with either Chiv's or Dodge's 4. 7 or 4. 8 Liter engines.
I used to drive a 10-wheel dump truck, empty weight was over 20k, and the big engine would get 15 mpg. Compare that to my Dodge, pulling 20K lbs with a 5. 9L or 6. 7L engine, and I get 10-12. BFCU's are better with the big motor, and it will get better mileage. Same thing with a Cummins C motor vs our B motor, BFCU numbers are better with the C than the B motor.
SOLER
Attention: TDR Forum Junkies 
