OT-OF-Here

Early on with the introduction of the new 600 this past year much was said about the lousy gas mileage. As it happens I had owned the early '04 305 and traded it on the '04.5 when I saw what I considered to be enough changes that should be upgrades that would warrant the trade. My 305 while only having 5500k on it when I traded it in was giving me 17.5 mpg at the time of the trade. My 04.5 now has 9300k and with this last tank hand calculated I got 17.8 and that was with at least 90% being in-town driving. Guys I don't think we got a bad deal here with this new truck and I know it took them awhile to get the reflashes out and such but I can say I'm pleased with this mileage pushing a 7500lb truck around. My $.02.

wyosteve

I agree with you. My truck new was in the mid 16's and has gone up since. I know some of the 600's did get terrible mileage so I guess I got lucky. There was an interesting thread on one of these sites a few days ago. It dealt with fuel mileage on 2nd gens. particularly 01's and 02's. The majority reporting their mileage were in the 15 to 18 category just like the 600's.

AKram

15,000 miles and I have the reflash and guess what ??? I average 10.7 MPG.

Pipes

Between towing my 20 ft car hauler and not, I average around 10 mpg with it and around 14 mpg without the trailer. Not to bad considering the weight of the unit, around 8200 kgs total. I just turned 18,000 kms I heard that mileage will improve as the truck breaks in. I have never hit 16 MPG yet.

doug

As an interesting aside, I had an interesting encounter at my dealer the other day. I took it in for the high idle TSB, knowing that it probably wouldn't apply (its for autos only) but I wanted to force the dealer to confirm that. They confirmed this, but gave me the fuel economy flash. yea, the one for 600s. mine is a 305.

Turns out that the early 04 trucks take the SAME fuel economy flash as the 600s do! Even though the TSB says it applies to the 600 engine, my dealer found that the ECM module identifier itself (on the truck) indicates that this TSB applies, even though the 305HP engine is behind it.

So I had the 600 fuel economy TSB applied to my 305 HP truck! too soon to tell if it made any difference in fuel economy; I typically get 18-19 unless I drive 75, in which case I get 17.5. Thats bone stock.

But on a similar note, I looked under my truck the other day and discovered that the stock muffler cried out that it no longer wanted to be at my service or be my humble servant. . I said to myself, "self, you must do something about this over the holidays!". I'm aware of anectotal evidence from 100Proof that exchanging the stock muff with one that breathes has improved fuel economy by perhaps 1 mpg. Has anyone else claimed a fuel economy improvement with exhaust?

OT-OF-Here

My comments were generated from a baseline of 13.1 mpgs when I got the truck and now that I have a few miles and have towed heavy with it then I am now getting more in keeping with what I had in mind when I purchased the truck. Content.

ed paul

the muffler is the cheapest mod u can do except for a drop in air filter,,and it won"t void ur warranty,,,,,,go for it!

swansong04

so your saying you got the re flash done and your still around 10.7 mpg on the over head ?? hmmmmmm sounds just like my truck and i drive the thing oh so gingerly to try to get the best mileage !!! i can drive my truck on cruise for a 100 miles, on a flat freeway, @ 60 mph and I'm lucky if i hit 16 mpg !!!

RamWheelsBy4

My 04.5 325/600 started at about 12.5mpg city and 15mpg highway. I have had the Flash 18-037-04 and it did not change actual milage, just the overhead now reads high instead of low.

I started using Power Service Kleen about 6 tanks ago and the milage has improve about 1 - 1.5 mpg. Now around 13.9 city(stop/go) and 16.5 highway(75mph). At 12k miles now and hoping it improves more.

It is still lower than I expected from a diesel.

OT-OF-Here

Just to offer a little help for those still having poor mileage, .....based on my own learning experience and having lived through the flash and having had all six injectors replaced,....nothing will help you more than pulling something heavy. NOTHING! I'm talking about 10k to 15k AT LEAST!!! Beg, borrow or steal, but pull something heavy and the sooner the better for your truck. You won't regret it. These trucks we made to handle heavy loads and everything seats in properly when you pull heavy. Several pulls are especially good and I would say think along the lines of a couple hundred miles of pull to make it happen properly. Pick a route that taxes the engine a bit with some good hills. Besides the benefit of better economy you will see the truck performing much better even if it's totally stock. Try it,...you'll like it.

doug

I have also heard of fuel economy improvements as late as 50,000 miles when no towing is involved. it takes a while to break these things in...

Diese

My younger brothers borrowed my truck last week for there Caribou hunt. 3078 miles in 7 days. Overhead and all that was reset as they left the driveway.

3 guys with gear
100 gallon fuel tank in the bed (full whole way there)
No trailer

overhead was check upon arrival. 17.8. Very nice (never toutched whole trip)
last flash 18-037-04

i cant believe some of the low numbers you guys are getting.

EDIT. 11,000 miles now, This truck has never towed anything (yet)

Shovelhead

There's a huge difference in MPG between cruising all highway & stop & go.
That 6,000 pounds that we have to get moving.
More if you have "Training Wheels" like me.

Diese

Agreed Ed, but 10 mpg is way low....

AKram

Thanks, but my first tow was from the dealer in Spokane Wa to here in Fairbanks Alaska towing a 24' inboard jet boat. Quite a few miles with a large load. I have further towed the boat all over the state and my mileage still is poor at 9.2 average towing. Dont get me wrong I still love the truck its much better than my Ford PSD ever was I just wish it would get better fuel economy.