I have been reading alot of people getting 14-15 mpg in the city and around 20 on the highway. I am getting about 15 in the city, depending on how power hungry i get but on the highway i am only getting 16 to 17 mpg. Just wondering if this was normal for a 2003 7.3 or if i should be doing some maintinance to get better mpg. I am about to take a trip from wisconsin to nyc and it would be great to get the 20 mpg on the trip. I have done the kwik filter and 5" exhaust but other than that the truck is stock. Also if there are any mods that will help with the mpg that you guys know about that would be great. Any advice is much appreciated. thanks guys

 

Tunner/Chip, Proper tire inflation, Fuel additive this might give you a few extra miles. If you do the Tunner or Chip please get gauges.

 

Model, weight, speed?
I drive my 9100 lb flatbed at 70 MPH.
I am happy recording anything above 10 mpg.

 

I have a stock 2003 Excursion w/ a 7.3 and do about the same. I am budgeting for mods, probably doing intake, then exhaust, gauges, and DP chip.

 

Yeah, I'm part of that club. I'm happy to make 13 empty and 9 pulling the trailer.

 

Ponch, I never saw above 18 until I put a bed cover on. It makes no difference in town, but gave me over 2mpg on the highway.

You can lower the tailgate to improve highway mpg, but do NOT remove the tailgate. The tailgate on my company F150 was recently stolen. Highway mpg dropped from 13.8 down to 12.4. Put a new tailgate on after 7 weeks without and am back to mid-13s.

 

This was proven false in several studies.

Milage for the PSD's will vary depending on gears, tranny, driving style, mods, and altitude. 17 mpg on the highway is not bad at all. Adding a chip can either increase or decrease your milage, depending on your right foot. A bed cover can increase milage by a little on the highway (different airflow than just lowering your tailgate). Fuel mods can also yield higher mileage, especially if you are sucking in more air in the fuel than you should. Last, good maintenance will also go a long way, such as regularly changing your fuel and air filters, and keeping tire pressure up.

My best highway mileage is 18.2 with my mods. I have not had a chance to test my highway mileage with my new fiberglass bed cover. But my city milage has jumped from 14.5 to 16.1 mpg with the addition of the bed cover and moving to Denver (I'm guessing altitude had something to do with it as well).

 

Yeah, I saw that episode, too. As much as I enjoy Mythbusters, their methods are frequently less than rigorous enough to get good, repeatable results. And as for newspapers, the only thing these guys routinely get right is their byline.

I read summations of two recent university studies on pickup truck aerodynamics some months back - these were done in controlled condiditons in a windtunnel. That means, all the variables, from temperature to barometric pressure, could be accounted for - and other things, like tire size, design, and pressure, engine tuning, quality of fuel, road conditions, hills or lack of, cruise-control or not, and anything else could be eliminated from clouding the conclusions about AERODYNAMICS, not fuel mileage.

One was not very comprehensive and simply compared aerodynamic drag on a pickup truck with and without the tailgate - it debunked the myth that removing the tailgate reduced drag. I also read a newspaper article that referred to this study and extended it to lowering the tailgate - a claim the original study didn't discuss.

The second study was more comprehensive. It proved that length of the bed has a large influence on whether or not a change in tailgate has any effect. They found:

with an 8-foot bed
1) lowering the tailgate reduced aerodynamic drag a little over 10%.
2) a bed cover reduced drag by around 15%.
3) removing the tailgate INCREASED drag compared to tailgate up.

with a 6-foot bed
1) lowering the tailgate didn't reduce drag.
2) a bed cover was better, improving drag a little less than 10%.
3) removing the tailgate increased drag compared to tailgate up.

with a less-than-6-foot bed
1) lowering the tailgate or adding a bedcover did not significant affect drag.
2) removing the tailgate STILL increased drag.

The explanation about lowering the tailgate was NOT that it removed the "sail" effect of the tailgate sticking up in the upper airstream, but rather that the lowered tailgate maintained a slightly longer separation between the two airstreams - one flow over the truck and one under - and allowed them to mix more smoothly (with an 8-foot bed). Allowing the two airstreams to mix too soon and too abruptly apparently creates huge turbulence.

Lowering the tailgate apparently allows the tailgate to maintain the separation a bit longer - long enough to help if you have a long bed pickup - but is no help with shorter beds. Removing the tailgate may remove the "sail", but that apparently is unimportant compared to keeping the under/over airflow from mixing too abruptly.

Of course, your results may vary, since this was a very, VERY controlled study that didn't take into account anything but aerodynamics - and only aerodynamics of the model they used for the study (I think it was a late 90s Chevy, but I don't remember).

 

By the way, I keep decent records. My mods improved my fuel mileage some, but not a lot. In town, all put together my mileage has improved from a little under 14 to a little over 15 (if I'm driving it - if my wife drives it, the mpg drops over 1 mpg). On the highway, my mods (prior to the DP Tuner chip) increased my mpg from just under 17 to just over 18. Again, only a little over one mpg. With my bed cover, I get over 20mpg (again, prior to the DP Tuner chip) - 2+ mpg increase with the bed cover. I have not yet had an opportunity to drive freeway long enough with the DP chip set on "econo" mode to tell whether it has increased my highway mpg. I know it doesn't help my city driving

As for driving with the tailgate down - I tried it and kept records (before deciding to spend all that money on a bed cover). I saw an average increase of 1.3 mpg by just keeping the tailgate down on the highway. Only about 7%, but it was definitely statistically significant. Oh, not just ONE tank, by the way. This was over several months and several relatively long trips - until I could spring for a bed cover.

Since going back to work full time after recovering from my knee surgery (full time is over 55 hours/week, right? ) I've had no time for highway trips. When I do (IF?), I'll record it and report my results. But it would have to be a sufficiently long trip to be meaningful. 50 miles, 100 miles, 200 miles - these are too short to get any kind of real picture.

I also keep records on the company truck and it suffered GRIEVOUSLY from its missing tailgate.

EDIT PS - I suffer under no illusions that everyone will have the results I did. That is why the wind tunnel test is so important for explaining aerodynamics - it removes variables in truck design and everything else that could cause me to get a 7% improvement with tailgate down, while Joe Schmoe down the street could get a 7% reduction with tailgate down.

In other words - experiment - if you keep good records and find that your truck benefits from tailgate down, then do it. If you find that your truck does NOT benefit from it, then you know better.

And, if you keep good records, you'll also - unfortunately - discover that most mpg improvement claims are bunk.

 

Great info on the tailgate studies!! Do you know where that info is on the web or print - I'd like to send it to a friend.

My mileage was great after the first few mods but recently, after my external fuel regulator and a change to Rotella Synthetic. The mileage dropped when not loaded. With a 9K lb. 5er I got 11 to 11.8 on highway and celebrated. But in town mileage dropped to 13 or so and highway about 17. Was getting 15-16 in town and 18-19 on highway. Not sure what happened???

 

I agree , the best I have seen in 18ish, although I have not owned the truck for long, I have put on some 1000miles plus in last three weeks or so. My highway MPG varied from 17.5 to 18ish (all hand calculation). The lio-o-meter says I get over 22MPG though!
My trucks: 2000 Lariat LE, 7.3 L, Crewcab , dually, 36 K miles on it, Super chip and a whole lot of cosmetic updates!

 

pastormiketdk - I'll see if I can locate the comprehensive study - it was a fun read. Well, the SUMMATION was, I can't speak for the whole report. Most comprehensive scientific reports are best read when you are suffering a bit of insomnia. Better than any sleeping drug.

It must be available on the web, though I read it in a science journal. I'll find it somewhere...

Pocket - if you are getting an improvement with in-town mpg, I doubt you can credit the bed cover. Aerodynamics doesn't play much of a role until speeds get higher than typical city traffic. Something else? I'd LOVE to see an improvement to 16+ in town. If you find out what it was, please let us know.

 

I've been tracking my mileage over several tanks around town, and the last time I did that was after I added my chip. There are only 2 things that have changed since then, I put the bed cover on, and I moved to Denver. So like I mentioned in the previous post, a combination of the bed cover and change of altitude has made my city milage jump. I'm not sure which one was the more significant factor. Hey, I'm sure happy with that milage in town and with the lift and tires that I'm running.

 

You whine a lot about reliability of the experiments and several factors, that suppose to be addressed and then give us bunch of conclusion without a word saying where to apply them?
Myth Busters drove crew cabs, short bed and Fords (from what I was able to notice).
Each body style and model will have different results.
When lowering the gates might be advantage on vehicle A, could turn into disadvantage on vehicle B.
Aerodynamics is tricky science. Althought there are general rules and some mathematical formulas, the only proof is wind tunnel.

 

Quote:

Originally Posted by [b

Vijay[/b]]My trucks: 2000 Lariat LE, 7.3 L, Crewcab , dually, 36 K miles on it, Super chip and a whole lot of cosmetic updates!

NICE LOW MILES! I wish I could claim any less than 150k on my 02 Lariat, 7.3L, Crewcab, single rear wheel, with lots of rock chips and farm abuse, but still running strong.