dankellyweir

After a year of searching I finally picked up a 2012 Express 2500 4.8l with 134k today (Dish network cable van). Drove it home on the highway at 70mph with the cruise control on, for about 40 minutes. Discovered the DIC options to view "fuel economy" while at a traffic light 5 minutes after I got off the highway. It said my mileage was 7.8 mpg (empty)! Over the next 20 minutes of back roads to my house it went up to 7.9, 8.0 and 8.1 mpg. I knew the gas mileage would be lousy but I never expected THAT lousy - especially on the highway.
I have been planning on building it into a camper for some long distance extended trips but this is really going to make those trips SO much more expensive, especially fully built and loaded.
Is everybody with these very common vans getting that same mileage?

mountainmanjoe

Of course it did. When you're standing at a light, you're not moving. The vehicle is going zero miles for every gallon of fuel, so the reading will plummet.

Somebody probably reset fuel economy tracker before you bought the vehicle (didn't want you to see it) , so you started with a clean slate. The number right now will fluctuate a lot depending on your momentary fuel consumption, but over time as you accumulate more data, it will start even out and settle down to an average (which still won't be great. You're pushing a 5,400 lb van with the aerodynamics of a barn down the highway at 70mph with a baby 4.8L engine)

https://fueleconomy.gov/

evsnova74

About a year or so ago we started tracking our mileage using google sheets. I just wrote a simple formula that references the miles and gallons at each fill-up. The dash is surprisingly accurate. Our '09 extended with the 4.8L got reset when I put a new battery in it and I just started tracking it so don't have solid numbers but our '18 6.0L gets mid 15s pretty consistently:

dankellyweir

Thanks for your input - I hope you're right!
I was under the impression the reading was not a momentary reading but an "average" as the manual states, and during the next 20 minutes of non-stop back road driving at 45-50 mph that DIC display slowly bumped up from 7.9 to 8.1.
I've re-set, hopefully I'll get a better reading from scratch.

dankellyweir

Thanks EVSNOVA - if my numbers come up to near yours I'll be a happy "camper"!

Twscarp

Hi, my 2008 1500 Express with the go-cart motor 4.3l (according to MMJ) and 240k miles gets 15.4 mpg (empty) according to the computer and doing by hand. When I bought it in Florida back in 2015, was getting 20+ mpg on the way back to Ohio, 70-75 speed all the way on cruise control.

therewolf

Of course, YMMV, depending upon driving habits, but here's a couple old tricks, to help boost mileage. :

1. Change your transmission fluid, AND filter. Many times, towards the end of their life, transmission filters get
glogged, and start to have an adverse effect upon your mileage.
2. Keep regular tune-ups and oil changes.
3. Clean and wax the exterior of your vehicle, so it flows thru the airstream more efficiently. Especially important, on larger vehicles.
4. Be sure to use gas shocks(nitrogen), keep them changed, at close to the proper intervals, or when you notice performance dropping off.
5. Keep your tires at maximum safe inflation pressure.
6. Try to avoid "Run & Gun" driving/ Use the Cruise Control, whenever possible, and especially avoid undue speeding, hard take offs, and unnecessary hard braking.


All in all, remember : Less rolling resistance equals greater gas mileage.

Twscarp

Of course, YMMV, depending upon driving habits, but here's a couple old tricks, to help boost mileage. :

1. Change your transmission fluid, AND filter. Many times, towards the end of their life, transmission filters get
glogged, and start to have an adverse effect upon your mileage.
2. Keep regular tune-ups and oil changes.
3. Clean and wax the exterior of your vehicle, so it flows thru the airstream more efficiently. Especially important, on larger vehicles.
4. Be sure to use gas shocks(nitrogen), keep them changed, at close to the proper intervals, or when you notice performance dropping off.
5. Keep your tires at maximum safe inflation pressure.
6. Try to avoid "Run & Gun" driving/ Use the Cruise Control, whenever possible, and especially avoid undue speeding, hard take offs, and unnecessary hard braking.


All in all, remember : Less rolling resistance equals greater gas mileage.





All good, plus I use TOP TIER gasoline all the time.

dankellyweir

Thanks for the input folks I'll try filling up and running some errands (gently) tomorrow after re-setting the mileage calculator and see what I get - sure hope it comes up substantially. Heck - I could get one of those church cutaway buses for an AWESOME camping van and get 8 mpg. (I think).
Twscarp mentioned top tier gas - I've never had a "flexfuel" vehicle before. I have noticed that sometimes there is a gas pump with 85 octane "Flex fuel" at a cheaper than regular price. I'd have to think the lower octane would produce less power thereby less gas mileage so my inclination is to skip the "flex-fuel", is that accurate?
Thanks again folks.

evsnova74

You don't even have to wait for the dash to average out, you can see what you're getting every time you fill up. Just write down the miles on the odo, then next time you fill up, take the odo miles, subtract the previous number and divide that by the number of gallons that you put in. That'll tell you the average for that tank.