How good will it get?

Turtle n Peeps wrote:
...snip........ At full throttle one of the cars I drive uses about 5 gallons of gasoline per mile driven. :E

Lots of fuel mileage comments on the forum, but I believe 0.2 mpg is the lowest reported. How fast are you going at the end of that mile, about 250 mph?

Just for comparison... Mine empty in town 13.5 -15 keeping my foot out of it. Hwy at 70 mph is 17. Now pulling 8.0-8.5 in florida, if I am in a big hurry.. well just leave the fuel card on the dash.. You will need it in a moment! lol no seriously I got 7.5 one time when I was pushing it hard to get home due to an family issue. Still my favorite small block engine..

You might want to go on one of the big GM truck websites to see what other owners are reporting. I assume you're running a 3/4 or 1 ton truck since you're talking about the 6.0--not the 6.2. Those running 6.2's in 1/2 ton trucks brag about their power--and getting 1 mpg less than a 5.3 1/2 ton truck.

The Ford F250's with the 6.2 gas motor commonly report 14 mpg in town and 17 mpg on the open road--without carrying loads.

My son in law has a 6.0 3/4 ton pickup, and his fuel mileage has been dismal. What I don't understand is why he's just accepted it. I'd at least want to get the engine checked out on a high level scanner to make sure the truck's in perfect mechanical position.

My 2014 Dully (in my signature below) has less than 5000 miles now. I've not even done the first oil change. But the mileage (diesel) has improved since I first got the truck. It started at 10 mpg and it's now averaging about 15. Open highway, (long distance driving, not interstate, and towing) it last averaged 16. I was shocked. I think the longer it runs the better it's getting too. Go figure, but I'm NOT complaining. My last Dully averaged 10 mpg when I sold it. I was so disappointed with the new one only got 10 also. But that started changing rather quickly. I *don't* get it, but I sure am enjoying it!

The mileage change you are seeing is not from breaking in. I have no idea what the change is coming from but it's not because of the motor breaking in.

BSFC figures just change a handful of horsepower from brand new to fully broken in. And it would take more than a handful of HP to see the improvement you are seeing. 15% is HUGE!

There are lots of things that contribute to fuel mileage but the big ticket item when you see a big change in fuel mileage is fuel. It has been reported over and over that some fuel suppliers are cheating on the amount of alkie they are putting in the fuel mix. I have personally seen fuel reports that show a 2 to 3% "difference" in alkie content from station to station around here. Others have reported that they have seen a 10% difference.

Another BIG ticket item is driving habits. When something is brand new most people have a: "lets see what this puppy can do" attitude even though they don't want to admit to it. After they have their car of truck for a few years that changes to a "no big deal" attitude and the mileage gets better.

With big HP engines we see now days is just astounds me how much fuel an engine will use when I flooring it once or twice a tank full. At full throttle one of the cars I drive uses about 5 gallons of gasoline per mile driven. :E

downtheroad wrote:
Our diesel kept getting better up to about 15-20k then leveled out.
Maybe also you subconsciously changed your diving habits slightly (lighter foot, smoother accelerations, etc.).

I hear that all the time about diesels, but not gassers. I may be driving a little bit better, although my cruising speed (70 mph) has not changed.

Our diesel kept getting better up to about 15-20k then leveled out.
Maybe also you subconsciously changed your diving habits slightly (lighter foot, smoother accelerations, etc.).