2015 silverado crew cab 1500 5.3 fuel mileage

[A.J._Langholff]

Ok guys I've been keeping track of my fuel economy the last couple of weeks & I've noticed that if I use the old fashion way of checking your economy there is about a 2 mile/ gal. Difference for example I drive 80 miles to work round trip, I filled my truck all the way up I reset the trip I went 471 miles & then I filled my truck back up to the top it used 23.9 gallons of gas so I do the math & it comes to 19.71 mpg but the truck told me I only got 17.6 mpg on the trip calculator. Anyone else notice that?

 

Thanks guys just thought that was a little strange.

[RyanbabZ71]

moving to correct section

[A.J._Langholff]

Sorry new guy here

[ember1205]

The DIC in the truck CONSISTENTLY reads higher than actual, and by a fair margin. I use Fuelly to track my mileage over longer periods of time, reset Trip A at every fillup, and never touch Trip B. Trip B is a solid MPG+ higher than actual over the life of the truck as tracked by Fuelly, and Trip A is consistently .5-1 MPG higher than actual.

 

If you're calculating actual to be higher than what the DIC is showing you, you're doing something wrong - the DIC is -never- below actual.

[A.J._Langholff]

Well that's what I'm getting it's saying 17 & I'm getting 19 ish...

[ember1205]

Try tracking with Fuelly to get the longer-term averages and check that against the DIC as well (just don't reset the trip odometer). The longer term you use for tracking, the more accurate the hand-calculated numbers will be. And, letting the DIC track for longer durations should allow it to be more accurate overall as well.

[fondupot]

My DIC usually reads about .5 mph higher than what I manually calculate. I use fuelly to track all my fillups as well.

[Eddie 70]

I've been using aCar for years now. I am sure it does about the same thing as fuelly. I am showing 24.3 over a 3500 miles on the DIC. aCar shows 23.29 over the same time period. I am happy with those numbers but would be really happy with calculated to be higher than the DIC.

[SkiDooNick700]

I'm sure someone has thrown this out there before, but I mean isn't the DIC pretty accurate? I notice mine reads about .5 to 1mpg higher on average, however, how do I really know how much gas is in the tank? Unless you keep pumping in gas until it overflows, we don't really know if it is "full". Think about it. if your manual calculation is off by .5 to 1 mpg, that could just be your margin of error of how many gallons you think are in the tank and if you filled it to the same spot as before.

 

Ex)

100 mile trip, I put back in 5 gallons. That's 20 MPG

100 mile trip, I put back in 5.5 gallons. That's 18.1 MPG

 

.5 gallon difference and your hand calc number gets thrown way off.

 

So, if you are saying your DIC is reading ~2mpg less, well maybe you're just not filling the tank up enough to get an accurate number and your DIC is in fact giving you an accurate number.

 

I've given up hand calculating after 6,000 miles. My number was always about .5 lower.

[ember1205]

Using Fuelly, I look at the long-term numbers and trends as opposed to what the latest fill-up shows. If the amount of fuel in the tank varies by as much as a gallon at any given fill-up, that error gets distributed over up to about 400 miles maximum. That same error margin gets distributed over thousands and thousands of miles when you track for the long term instead.

 

A quick example based on the following assumptions: Each "fill-up" is done after 350 miles of driving. A completely full tank would consist of 22 gallons, each fill would max out at 21 gallons possible, but the actual fill each time is exactly 20 gallons. Margin of error for every fill up is up to one gallon.

 

After one fill-up, I have 350 miles and 20 gallons. Hand-calculated, I would be at 17.5MPG. If I actually only burned 19 gallons (off by a gallon on the previous fill), I would have 18.4MPG. If, instead, I needed another gallon but stopped short, I would have 16.7MPG.

 

After ten fill-ups, I would have 3500 miles and 200 gallons. Hand-calculated would be 17.5MPG. If, on the most recent fill, I really only needed 19 gallons, I would hand-calc 3500 miles against 199 gallons and get 17.6MPG. If, instead, I filled a gallon short, I would have 3500 miles over 201 gallons and hand-calculate out to 17.4MPG.

 

If I needed 21 gallons on every fill up but only put in 20, I couldn't sustain that as the level in the tank would decrease by a gallon at each fill up.

 

The longer I go, the more "stable" the MPG becomes over time. And, any one tank that is off will show as a sort of anomaly. From there, I can watch the next few tanks to see if it's a seasonal change (winter blend versus summer blend fuel), driving habits, or maybe there's something off with the vehicle.

[TxTruckMan]

Averaging over several tanks is definitely more accurate. The only unknown at play there is the accuracy of the pump. The DIC appears to be 5% off. What do you think the accuracy of the pump is?

 

Just Googled it. Pump accuracy appears to be between .3% and .6% unless they're out of spec, which happens ~5% of the time. So definitely more accurate than the DIC.

[SkiDooNick700]

Using Fuelly, I look at the long-term numbers and trends as opposed to what the latest fill-up shows. If the amount of fuel in the tank varies by as much as a gallon at any given fill-up, that error gets distributed over up to about 400 miles maximum. That same error margin gets distributed over thousands and thousands of miles when you track for the long term instead.

 

A quick example based on the following assumptions: Each "fill-up" is done after 350 miles of driving. A completely full tank would consist of 22 gallons, each fill would max out at 21 gallons possible, but the actual fill each time is exactly 20 gallons. Margin of error for every fill up is up to one gallon.

 

After one fill-up, I have 350 miles and 20 gallons. Hand-calculated, I would be at 17.5MPG. If I actually only burned 19 gallons (off by a gallon on the previous fill), I would have 18.4MPG. If, instead, I needed another gallon but stopped short, I would have 16.7MPG.

 

After ten fill-ups, I would have 3500 miles and 200 gallons. Hand-calculated would be 17.5MPG. If, on the most recent fill, I really only needed 19 gallons, I would hand-calc 3500 miles against 199 gallons and get 17.6MPG. If, instead, I filled a gallon short, I would have 3500 miles over 201 gallons and hand-calculate out to 17.4MPG.

 

If I needed 21 gallons on every fill up but only put in 20, I couldn't sustain that as the level in the tank would decrease by a gallon at each fill up.

 

The longer I go, the more "stable" the MPG becomes over time. And, any one tank that is off will show as a sort of anomaly. From there, I can watch the next few tanks to see if it's a seasonal change (winter blend versus summer blend fuel), driving habits, or maybe there's something off with the vehicle.

 

Interesting point, thanks for bringing that up!