Mpg 6.4 vs 6.7

[Jonnydime]

So around the same time I bought my 08' a friend of mine bought an 11'. After about 4 months I think it is safe to say the idea that the 6.7 gets more Mpg's is junk. I have an 08' F-350 cclb FX4 with 3.73's and stock wheels and tires. He has an 11' F-250 extended cab short box FX4 with 3.55's I believe. So long story short he is getting 11 MPG and I am getting 13.5 MPG. Both hand calculated. Both trucks are stock.

[08F250TX]

Different driving habits could be playing a part in it.

[Alberta Advantage]

There are so many variables to take into consideration other than the displacement of the engine that you can't even compare the two. When engines are new, they suck done fuel. I had bills for $700/month for premium fuel in my Infiniti G37 coupe when it was brand new. Now, I'm down to about $300/month since it has 15,000 miles on it. Engines require a period to break in. Gears/configuration of the truck, the weight of the truck, driving habits, highway driving, city driving, idling time, tires, etc., all play into the fuel economy equation. I can see a huge spike in fuel economy on the 2011 versus the 6.4 PS when it comes to the trucks being in regen.

If I wanted fuel economy, I'd buy a bus pass.

[sanman28]

Originally Posted by Alberta Advantage

There are so many variables to take into consideration other than the displacement of the engine that you can't even compare the two. When engines are new, they suck done fuel. I had bills for $700/month for premium fuel in my Infiniti G37 coupe when it was brand new. Now, I'm down to about $300/month since it has 15,000 miles on it. Engines require a period to break in. Gears/configuration of the truck, the weight of the truck, driving habits, highway driving, city driving, idling time, tires, etc., all play into the fuel economy equation. I can see a huge spike in fuel economy on the 2011 versus the 6.4 PS when it comes to the trucks being in regen.

If I wanted fuel economy, I'd buy a bus pass.

Sorry....no. Engines do not have a break in period these days.....let alone, one that cuts fuel consumption by more than half....and out of a jap car. Your right foot is problem.

[Alberta Advantage]

Originally Posted by sanman28

Engines do not have a break in period these days.....

So why is it recommended in the Infiniti's owner's manual that you drive 600 miles with no hard acceleration, no high rpm, no excessive/hard braking for 200 miles, and no maintaining a constant speed for a long period of time during these initial 600 miles?

[Jonnydime]

Thanks for raining on my parade. So the fact that my truck has less power weighs more and has lower gearing some how makes it more efficient.

Originally Posted by Alberta Advantage

There are so many variables to take into consideration other than the displacement of the engine that you can't even compare the two. When engines are new, they suck done fuel. I had bills for $700/month for premium fuel in my Infiniti G37 coupe when it was brand new. Now, I'm down to about $300/month since it has 15,000 miles on it. Engines require a period to break in. Gears/configuration of the truck, the weight of the truck, driving habits, highway driving, city driving, idling time, tires, etc., all play into the fuel economy equation. I can see a huge spike in fuel economy on the 2011 versus the 6.4 PS when it comes to the trucks being in regen.

If I wanted fuel economy, I'd buy a bus pass.

[usnavyad]

I haven't heard of anything like a break in point with the invention of fuel injection and tps sensors its mad to not change at all lol unless Like the fuel rails are getting clogged over time with time gas mileage should drop not go up lol

[Clayton1985]

Originally Posted by sanman28

Sorry....no. Engines do not have a break in period these days.....

There's alot of people who will disagree with this.

[spideygsm]

The mpg's on my 6.4 suck. Don't buy a 6.4 if you think you're ever going to get more than 11-13 average mpg's unless you drive all hwy. Deleting the emissions isn't an option for me. Some people claim it helps.

I also wouldn't base your decision between the two trucks based solely on gas mileage.

[Dim Sum]

Manual on my new 6.7 says 1000 miles no cruise control and 500 miles no towing. I did a trip to Cincinatti yesterday and ran a bunch of errands.

I started out with 209 miles and a full take of diesel. I ended the day with 534 miles and a full tank of diesel.

My first tank, empty, with a regen leaving the fuel station and regen about 20 miles from home was:

327 miles / 17.6 gallons = 19.58 mpg.

For a trip with two regens, I'd say that's phenomenal mileage. I never got that mileage in my 6.4...even babying it with the H&S tuner.