So, just completed my first trip of any length with my new (to me) 2014 Ram 2500 CTD. TT is 2016 Prime Time Lacrosse.Traveled over 1200 miles combined. Fuel mileage towing averaged right at 11.5 MPG. Combined local commute and towing was 12.7.This was hand calculated. The computer said I was getting 12.7 towing and 13.7 combined commute/towing.Just goes to confirm that at least on the Ram, the computer calculation is about 1 MPG off reality. Saw the same with my previous rig (2011 GMC Sierra 1500).Computer read out is interesting conversation, but just confirms that is all it is and has limited application to reality. What I can now do with some degree of accuracy, is subtract 1 MPG from whatever the computer reads, and I will be within a tenth or two of reality.Mike

When towing, I estimate 10 mpg (diesel), and take that as a base-line for my costs. If traveling 1200 miles round trip, that would equal 120 gallons. 120 gallons multiplied by $2.00 a gallon would be $240.00 for fuel for my trip. I add in another 50% contingency for local running around and side trips. So that $240.00, add on another $360.00 for fuel costs for this imaginary trip. I then make sure I have the $360.00 available at the start of the trip and go have fun!Simple, works for me. And when the end cost IS less than this, the remainder gets tucked away as a start (savings) for the next trip.Local daily driving, fill it as it's needed. No problem.Now that you have somewhat of a baseline ... about 11 mph, you can easily estimate the costs of your future trips.

My 2013 and my 2005 Rams have always been with-in a tenth or two from the lie-o meter.

My last two trucks have been about 0.5 miles better on the computer than hand calcs.

I don't really look at the absolute numbers, but for change in the numbers. If mileage starts dropping once you have a baseline, it's time to find out why.

Bedlam wrote:I don't really look at the absolute numbers, but for change in the numbers. If mileage starts dropping once you have a baseline, it's time to find out why.I agree. DW car started to drop which lead me to a stuck brake caliper.

Just confirmed what alot of folks already know | Good Sam Community

TomG2
Explorer
Apr 04, 2016
I like the computer generated numbers. Trouble is, my billfold has to deal with reality.
transamz9
Explorer
Apr 04, 2016
Bedlam wrote:
Nah, they wouldn't do that. It's so all the rednecks can run oversized tires and not get speeding tickets. Those that run stock height can brag about their top speed on the two-lane because when was the last time you heard a redneck brag about mileage?

I don't brag about it but my 2005 does get pretty good mileage even with oversize tires. It actually does a little better than my 2013 if I keep the smoke to a minimum. Now I need to go get this red stuff off my neck.:B
Bedlam
Moderator
Apr 04, 2016
Nah, they wouldn't do that. It's so all the rednecks can run oversized tires and not get speeding tickets. Those that run stock height can brag about their top speed on the two-lane because when was the last time you heard a redneck brag about mileage?
Walaby
Explorer II
Apr 04, 2016
TomG2 wrote:
My Silverado and F-150 are off by similar amounts. About 5-8 percent optimistic.

Makes me wonder if vehicle manufacturers do this on purpose. Lets fool the public into thinking they get better gas mileage than they really do.

Wouldn't surprise me.

Mike
TomG2
Explorer
Apr 04, 2016
My Silverado and F-150 are off by similar amounts. About 5-8 percent optimistic.
eichacsj
Explorer
Apr 04, 2016
Hand calculating has a lot of variable; same pump, (each pump, ea station can have different calibrations, slight yes, but still different), fill it up exactly each time, time of day, same temp, elevation (as IdaD commented), rounding, speedometer accuracy. The vehicle computer; distance / fuel flow rate. The major variable is tire wear (speedometer accuracy).

IMO - Vehicle computer is more accurate but it is fun to compare, I do.
IdaD
Explorer
Apr 04, 2016
Mine has read a little high and a little low when I've checked it but it's always been fairly close. I don't use the same pump to fill up every time (nor is it always the same temperature, elevation and etc.), so I'm not sure hand calculated is a whole lot more accurate.

It's close enough not to worry about it either way. In general I'm going to spend quite a bit on diesel every year. A bit better or worse mileage here or there isn't going to make much of a difference in the scheme of things.
fla-gypsy
Explorer
Apr 04, 2016
If mine changes significantly I look for a problem, otherwise I just fill it up as needed and don't worry about it.
Walaby
Explorer II
Apr 04, 2016
Yeah, biggest thing for me was establishing a realistic baseline. Which is what I was able to do this last trip.

Dutchmen - I do the same thing..rough wag on gas cost as a planning figure for now.

Transamz9 - if you're that close to the lie-o-meter, congrats. None of my vehicles have ever been that close. Jeep Grand Cherokee, two Dodge Rams, Dodge Challenger, GMC Silverado.. have never been that close.

Im really pleased with the Ram thus far. Fuel mileage towing that is within spitting distance of in town daily driver mileage. Towing ability that is rock solid and deceptively smooth.

This truck/trailer combination is it for me for the foreseeable future.

Mike
45Ricochet
Explorer
Apr 04, 2016
Bedlam wrote:
I don't really look at the absolute numbers, but for change in the numbers. If mileage starts dropping once you have a baseline, it's time to find out why.

I agree. DW car started to drop which lead me to a stuck brake caliper.