I recently purchased a 2015 6.7 F-450 King Ranch, all stock, with approximately 35000 miles on it. The truck is amazing. I did not buy it for the fuel economy but I am curious what the average MPG's everyone is getting with theirs. This is my first F-450 and I am told it has the 3.55 gears. The tires are a 19.5, not sure if that is standard or not. On a recent 1700 mile trip pulling my 38' 5th wheel toy hauler, I calculated a 6.5 mpg. The toy hauler loaded is approximately 17000 lbs. The first half of the trip I drove an average of 65 mph. The second half I drove 70-75 mph. there was not much difference in fuel consumption by adjusting my speeds. Just wondering if this is normal as even my under powered 7.3 pulled this rv and managed 11 mpg.
I believe all 450's come with 4.30 gears…certainly not 3.55's. My F350 DRW tows the same weight with 3.73's. I average 8-9.5 depending on wind. I run at about 68-70 which has me at about 1750-1800 RPM. 70-75 is pretty fast for 4.30 gears. You may have had wind in your face as well. I got down to 7.5 once towing in very heavy headwinds. Not much wind it is usually around 9-9.5. Highest has been almost 11 with a strong tail wind. I averaged all my towing miles a couple of days ago and was at 8.7mpg over about 4K miles. Truck has 6.5K miles on it so it may get a little better.
The rear axle code says "4L"?. The best I have been able to get at 65 mph, with the truck only is 12.5, maybe these averages are normal. This is my first with a 6.7 and an F-450. Just comparing with others who have had more time/experience with a similar truck to see if I am in the same ballpark or if I have a mechanical issue of sorts. Now I see why there are so many discussions on crazy mods to assist with MPG'S. I personally am not into aggressive modifications but am open to ideas that may give small gains without heavy modification. Thankfully I only use the truck for vacations.
The 4L code is for a 4:30 geared axle with limited slip. It's a big heavy truck with a lot of gear in it. I don't think anything is wrong with it. The best way to increase your mileage with that load is to run a little slower. I lose 1-1.5 mpg kicking my speed up to 70-75. That's a big penalty. Trailer tires are rated for 65 mph so it's not a bad idea to hang around that speed. Mine gets 15-16 running around country roads at 55-60. I have never been on the highway…70-80 here in Texas for a very long time without the 5th wheel.
2015 F450 King Ranch pulling a 17000 lbs 5th wheel. Depending on winds I've averaged as high as 9 doing 65 to a low of 6 doing the same. We have 4:30 gears.
All F-450 pickups are 4x4, come with 4.30 gears and 19.5 wheels as standard, no options available. I also have a '15 F-450 KR and pulling a heavy load I'll average about 8 mpg. Speed is your enemy here. Your truck will pull that load about as fast as you want to go but it's going to use a lot of fuel. Try to keep it around 65 mph. Might want to change the air filter and fuel filters unless you know they've been changed. We don't have winter fuel here but if you still have it that may cause some of your mileage loss. I use Motorcraft PM 22 fuel additive with every fill-up to add lubricity to the fuel and increase the cetane level.
Very true. I had a '12 F-450 so I am aware of the 17's. They still had the 4.30 as the only available axle ratio. I believe the OP was referring to his '15.
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