New Ram is awsome!

Many years ago, an older gentleman told me that there are two things many men lie about.....fuel mileage and their sex life. I think the engineer/ computer programmer that developed the software for the Ram “Lie- O -Meter”.....was one of these men! :B memtb

BurbMan wrote:
First road trip 2 weeks ago, sadly no camper yet, but was loaded up with RV parts from the Elkhart surplus stores!

Had the cruise control set on 75 for most of the trip, LI to IN in about 10 hrs. Laramie trim makes for a very comfortable ride, although a little bouncy, need that 3200 lbs of camper on the back to smooth it out!

You must have been bucking a head wind. Mileage should have been higher, based on my experience. Was the load above the cab? What was hand cal mileage? The tires now on the truck could be effecting mileage. My lie-o-meter always shows better mileage than my hand cal mileage. I always use the two additional clicks when fueling. First additional gets a little more in, second clicks off right away.

'16 Ram 3500 Cummins SRW with 54k (purchased new). Dream-meter has always read optimistically about 5-10%. Last fillup we hand calculated at 19.0 mpg (70 mph freeway driving empty). Dream-meter said 20.3 mpg.

Got 11 mpg pulling a 12k 5r. Get 12-13 mpg hauling an almost 4k in-bed camper at 65 mph. Amazingly, if we slow down to 55 mph (w/camper), mpg's jump up to 14-15! All hand calculated.

RobWNY wrote:
My comment regarding the computers not being very accurate is from my experience. I have a 2017 Ram with the 6.4 Hemi. On my last tow, the computer said I got an average of 9.7 MPG. The hand calculation showed I really got 6.9 MPG. That's a huge difference. Of course my fuel gauge isn't very accurate either. I have a 31 gallon tank. I ran my truck to near empty (not towing) and when the computer said I was 27 miles to empty I put gas in. It took 24.3 gallons so I had nearly 7 gallons left in the tank.

I've literally pulled into a gas station not more than a few blocks after the fuel light came on. I still had 8 gals left after filling up. The gauge is way under 1/4 when the light comes on but I always seem to have 7-8 gals left.
I have never seen 9.7. In fact I'm lucky to see 9 mpg from the computer.
Don't hand calc as that would most likely ruin a good camping trip.

kellem wrote:
I always buy big 2500 series trucks pulling significant weight with fuel mileage being top priority........oh, is there a reset button on the lie-0-meter ?

Yes! But, it’s a very persistent liver! ;) memtb

I always buy big 2500 series trucks pulling significant weight with fuel mileage being top priority........oh, is there a reset button on the lie-0-meter ?

BurbMan....first, Congratulations on choosing one of the finest tow vehicles for the RVer. But, and there’s always the “but”...... many Ram owners refer to the computer as the “Lie-O-Meter”! We keep a log of all fuel mileage (computer vs pen and paper), all maintenance, etc. If the computer is “ever” (very seldom) within 2mpg of the pen/paper number.....it’s an anomaly! And, in 140K + miles, has shown greater fuel mileage than pen/paper computed less than a dozen times. Many times off by 5 mpg or greater! In spite of that.....a great truck and tow vehicle! Congratulations......and to remain joyous, “never”, “never”, compute your mileage with pen and paper! :B memtb

My comment regarding the computers not being very accurate is from my experience. I have a 2017 Ram with the 6.4 Hemi. On my last tow, the computer said I got an average of 9.7 MPG. The hand calculation showed I really got 6.9 MPG. That's a huge difference. Of course my fuel gauge isn't very accurate either. I have a 31 gallon tank. I ran my truck to near empty (not towing) and when the computer said I was 27 miles to empty I put gas in. It took 24.3 gallons so I had nearly 7 gallons left in the tank.

No, the computer does not know exactly how much fuel is used and it doesn't even know exactly how fast you are traveling due to varying tire pressure levels causing different tire diameters and other factors. The injectors only use the amount needed and dumps the rest back into the tank. There is no measure of exactly how much is used by each injector, only the time each injector opens/closes based on its fuel mapping. The computer mileage is just an algorithm.

I keep detailed records of almost every fill-up of all 8 vehicles I have owned for the past 15 years which ranged from two BMWs, a Ram 2500, F150 Ecoboost, F150 5.4, C6 Corvette, and a JK Jeep. I also recorded the computer mileage upon every fill-up. On tanks where there are very little stop/starts of the engine like the runs that TFL does in their tests, the computer is very close to calculated. On tanks where there are multiple stops/starts of the engine, it was off anywhere from 1-3 mph in every vehicles I have recorded. Generally, the more stops/starts of the engine the further off it was.

Also, the TFL loop does not use the mileage that each truck's computer says it has traveled. They use the actual distance of the trip, not the distance that the truck said it traveled. Not every vehicles speedo is 100% accurate and the standard for most manufacturers is a bell curve of about +/-3% the last I read. Tire wear and psi also effect the speedo which effects how many miles the vehicle's computer says it traveled which is what the ECM's mpg algorithm is based on.

goducks10 wrote:

RobWNY wrote:
Very nice truck. Congrats! The computers are never very accurate. Did you happen to write down the mileage and gallons used and check your MPG that way too?

Not too sure about that. After watching a few FLT mileage runs the computers were pretty close on Rams and even lower than the hand calc at times.

Always wondered why folks say they're not accurate. Doesn't the computer know exactly how many gallons you've used and exactly how many miles you've gone?

Personally I don't bother doing the hand calc. I figure the mpg display is close enough.