New 2022 Ram 1500 with Underperforming MPG

[SD Rebel]

I just picked up my Ram 1500 Laramie 4WD offroad edition with 3.92 rear axle. The EPA rating on the window sticker says 17 MPG city, 21 MPG highway, 19 MPG combined, but I'm getting about 12 MPG in the city and averaging about 15 MPG on highway. I am REALLY taking it easy on the driving and it shows it to be in ECO mode most of the time. I have zero additional mods on the vehicle. I didn't buy the truck for MPG, but I was expecting to perform relatively close to the ratings. This truck is performing almost 30% lower. My questions are:

1. Is the EPA rating on the window sticker based on the truck configuration or based on some base trim with none of my options? If it's based on some arbitrary configuration, then it is really misleading.

2. Do the HEMIs have a large break-in period before efficiency climbs back to normal range? My current mileage is only around 100 miles or so.

3. Does the higher octane fuel (89) that's required by the manual make a noticeable difference? I'm still driving on the full tank that the dealer provided and I'm not sure what they put in there. I am guessing that they used regular gas, but in my experience higher compression engines perform the same on lower octane fuel as long as there is no heavy knocking and I haven't heard anything while driving around.

1. The EPA rating is based on a similar configuration RAM (i.e. crewcab 4x4 w/ short bed), using 18" street tires and likely a 3.21 rear axle. Then RAM blanket states all variants, including OFP and Rebels with 3.92 and 33" tires. They aren't going to come close to the EPA rating.

This is a common complaint of how RAM does their EPA window stickers. It's been brought up by TFL truck for example on their Rebel. You are allowed exceptions to lower mpg based on variants, like GM does with the Trail Boss. But RAM decided not to do that, which I think is a bit shady by them.

2. Hemis break-in, but not close to enough for your truck to get in the window of the EPA rating.

3. Yes, for the best performance and mpg, you should use 89 octane.

However, you can kinda get close to the EPA rating is you drive really easy. I mean like an old person who isn't afraid of pissing off all the driver's behind them. If you drive like that, including the slow lane on the freeway, you can get surprising good mpg.

If I drive my Rebel like normal, I get 13 mpg, if I hypermile it, I can get 18 mpg combined, but it's zero fun that way. The other option is to get small all-season road specific tires, you will see a nice jump in mpg as well.

 

[BigHornDaddy318]

I’ve run thousands of miles on 89, 91, and 93 (with some ethanol-free 90, too). I’ve observed no noticeable difference (too many variables). My best ever economy was achieved on 89.

I have a 3.21 rear in my Big Horn might be the difference in mpg?

 

[SpeedyV]

I have a 3.21 rear in my Big Horn might be the difference in mpg?

Oh, absolutely. My point was that I’ve found no measurable advantage in fuel economy when running premium. Responsiveness…maybe. It seems the engine is indeed tuned for 89, as per the manual.

 

[StuartV]

Anyone reporting mileage that they got that wasn’t hand calculated is just reporting a guess.

I’ve seen people occasionally post that they checked their onboard computer by hand calculating and claim that their onboard computer is accurate. But, I have never yet seen anyone post that they have hand calculated on every fill-up and their onboard computer is accurate every time…

On the other hand, I have hand calculated every fill-up for 2 different trucks over a combined total of about 80K miles, and both trucks have been consistently high on what the onboard computer said. Every now and then the onboard is correct. And, I think 2, or maybe 3, times I actually got better than what the onboard said.

 

[Idahoktm]

Anyone reporting mileage that they got that wasn’t hand calculated is just reporting a guess.

I’ve seen people occasionally post that they checked their onboard computer by hand calculating and claim that their onboard computer is accurate. But, I have never yet seen anyone post that they have hand calculated on every fill-up and their onboard computer is accurate every time…

On the other hand, I have hand calculated every fill-up for 2 different trucks over a combined total of about 80K miles, and both trucks have been consistently high on what the onboard computer said. Every now and then the onboard is correct. And, I think 2, or maybe 3, times I actually got better than what the onboard said.

I hand calculated my mileage for the first couple of months I owned my truck and the computer was close enough that I only check every now and then. Every time I've checked it, it hasn't been off by more than .35 mpg. It's usually more accurate than that.

 

[Jako]

Anyone reporting mileage that they got that wasn’t hand calculated is just reporting a guess.

I’ve seen people occasionally post that they checked their onboard computer by hand calculating and claim that their onboard computer is accurate. But, I have never yet seen anyone post that they have hand calculated on every fill-up and their onboard computer is accurate every time…

On the other hand, I have hand calculated every fill-up for 2 different trucks over a combined total of about 80K miles, and both trucks have been consistently high on what the onboard computer said. Every now and then the onboard is correct. And, I think 2, or maybe 3, times I actually got better than what the onboard said.

32,920 miles - hand calculated every fill up. Discrepancy of .22 mpg, truck higher than hand calculated. My experience for the correlation between the two is closer when your driving is consistent on a tank of gas, for example all highway or all city.
It seems to me if I do all highway and than do city the accuracy is off and hand calculation can be either + or - in relation to the Ram's calculations.

 

[AMK53]

I got to do a long duration test driving from Houston to Denver (~ 1100 miles) and the largest factor is speed. When I highway cruise at 65 mph, it actually gets around 19 mpg on average. Every 5 mph increase dropped it by about 2 mpg until you hit about 75-80 and then it tanked. At 85 MPH it was averaging around 12 mpg. This was all over hilly highway on cruise control.

The 87/89 octane seemed to make no noticeable difference. I’m sure there is some change but it’s probably too small to notice in an uncontrolled environment (I.e. not on a dyno).

The computer seemed to get pretty accurate numbers to manually doing the math. It’s likely showing the right numbers all the time.

The big takeaway is that aerodynamics is the largest driver to not seeing the EPA ratings (in my truck configuration). Don’t drive it above 65 MPH if you want to save fuel. I’m sure the air suspension will help to some small amount if you can reduce the right height.

 

[Idahoktm]

I got to do a long duration test driving from Houston to Denver (~ 1100 miles) and the largest factor is speed. When I highway cruise at 65 mph, it actually gets around 19 mpg on average. Every 5 mph increase dropped it by about 2 mpg until you hit about 75-80 and then it tanked. At 85 MPH it was averaging around 12 mpg. This was all over hilly highway on cruise control.

The 87/89 octane seemed to make no noticeable difference. I’m sure there is some change but it’s probably too small to notice in an uncontrolled environment (I.e. not on a dyno).

The computer seemed to get pretty accurate numbers to manually doing the math. It’s likely showing the right numbers all the time.

The big takeaway is that aerodynamics is the largest driver to not seeing the EPA ratings (in my truck configuration). Don’t drive it above 65 MPH if you want to save fuel. I’m sure the air suspension will help to some small amount if you can reduce the right height.

Cruise control kills your mileage in hilly terrain.

 

[runamuck]

I dont do much city driving with mine. bought for towing our travel trailer and for travel. I always get around 20 on the highway and I normally cruise in the 75-78 range. I mostly set cruise and I only use regular gas. YMMV

 

[SpeedyV]

32,920 miles - hand calculated every fill up. Discrepancy of .22 mpg, truck higher than hand calculated. My experience for the correlation between the two is closer when your driving is consistent on a tank of gas, for example all highway or all city.
It seems to me if I do all highway and than do city the accuracy is off and hand calculation can be either + or - in relation to the Ram's calculations.

I think I’ve seen one time - just once - that the onboard computer wasn’t “optimistic”. Sometimes it’s off by more than 1 mpg! And I have tracked every tank with Fuelly (hand calculating) since new. I agree with @StuartV that it can’t be trusted.

 

[StuartV]

32,920 miles - hand calculated every fill up. Discrepancy of .22 mpg, truck higher than hand calculated. My experience for the correlation between the two is closer when your driving is consistent on a tank of gas, for example all highway or all city.
It seems to me if I do all highway and than do city the accuracy is off and hand calculation can be either + or - in relation to the Ram's calculations.

When I do road trips, I tend to fill up just as I'm leaving and fill up again at my destination, so I can see what my "best" mileage is. For example, I got home yesterday from a 600 mile round trip to NC and back. I filled up just after I left on Friday. When I got home and filled up, my onboard said 25.1. Fuelly says 24.1.

That also means the fill-up just after I left was a fill-up after 600 miles of mostly city driving. The onboard computer said 21.0. Fuelly says 20.08.

I don't think type of driving matters, as far as accuracy of the onboard computer.

I think you are very lucky that your onboard is accurate. I wish mine was. I also think you are by far an exception.

 

[SD Rebel]

As the owner of a Rebel, it's better to hide your mpg and just try not to think about it, it's never going to be reasonable.

But I will say, I've hand calculated my MPG, it's been within .5 to 1 mpg off, usually optimistic, which compared to previous vehicles isn't bad. At near 13 mpg, I rather not think about it

 

[Bigbags85]

And what did changing tires and rims cost?

I always have 2 sets of rims for every vehicle so I can just swap snows on in easily in the winter, I wasn't specifically looking for mpg just stating that the factory Falkens suck for mpg.

 

[monza2t]

I've spot checked computer MPG v. hand calc and have come up with +/- 0.5MPG. To me that's fine enough for accuracy. I don't need it to be more accurate than three significant digits, because really it is what it is and wanting such refinement doesn't change change anything. I just want to see an approximate value and to identify a trend down that might indicate a change in something.

 

[BowDown]

Anyone reporting mileage that they got that wasn’t hand calculated is just reporting a guess.

I’ve seen people occasionally post that they checked their onboard computer by hand calculating and claim that their onboard computer is accurate. But, I have never yet seen anyone post that they have hand calculated on every fill-up and their onboard computer is accurate every time…

On the other hand, I have hand calculated every fill-up for 2 different trucks over a combined total of about 80K miles, and both trucks have been consistently high on what the onboard computer said. Every now and then the onboard is correct. And, I think 2, or maybe 3, times I actually got better than what the onboard said.

Then you haven't looked. I hand calculate at every fill-up and compare it to the mileage computer and there's never more than .03 variance in my hand calc vs the computer. I average 420-430 miles per 23 gallon refills consistently and have for the last 45K miles

 

[BowDown]

I got to do a long duration test driving from Houston to Denver (~ 1100 miles) and the largest factor is speed. When I highway cruise at 65 mph, it actually gets around 19 mpg on average. Every 5 mph increase dropped it by about 2 mpg until you hit about 75-80 and then it tanked. At 85 MPH it was averaging around 12 mpg. This was all over hilly highway on cruise control.

The 87/89 octane seemed to make no noticeable difference. I’m sure there is some change but it’s probably too small to notice in an uncontrolled environment (I.e. not on a dyno).

The computer seemed to get pretty accurate numbers to manually doing the math. It’s likely showing the right numbers all the time.

The big takeaway is that aerodynamics is the largest driver to not seeing the EPA ratings (in my truck configuration). Don’t drive it above 65 MPH if you want to save fuel. I’m sure the air suspension will help to some small amount if you can reduce the right height.

I drove from Dallas to Houston and back last Saturday to pick up a Siberian Husky puppy, averaged 19mpg at 85mph.
What I have noticed is that my truck with 3.21 gears doesn't like 60-68 mph, the mileage in that area sucks compared to 71-75 mph which is in the 21-23 mpg range. 71-72 mph seems to net the best at 23 mpg. 74 mph drops to 21 mpg and 75 -78 nets me 20 mpg. I've found this over numerous Dallas to Houston and back trips.
I have seen that 93 impacts my highway economy by about 1 mpg and being that I fuel up at Costco, my options are 87 and 93 so I always use 93. What I did find over the summer is that 89 octane straight gasoline, no ethanol, returned zero gains. I expected to pick up something but it was dead identical to 93 with whatever % of ethanol they add

 

[SpeedyV]

Then you haven't looked. I hand calculate at every fill-up and compare it to the mileage computer and there's never more than .03 variance in my hand calc vs the computer. I average 420-430 miles per 23 gallon refills consistently and have for the last 45K miles

Wow! What you are seeing is unheard of (until now). My lie-o-meter averages more than 0.5 mpg high (over 30K+ miles, hand-checking every tank).

 

[HemiDude]

Maybe I'm missing the point to some of these observations, but are people really that concerned that their truck's mpg calculations are 1 mpg off? Even at 2 mpg off, are people driving their tanks low enough that it becomes a issue? Not trying to be d***, just trying to understand

 

[JF19Longhorn]

Anyone reporting mileage that they got that wasn’t hand calculated is just reporting a guess.

I’ve seen people occasionally post that they checked their onboard computer by hand calculating and claim that their onboard computer is accurate. But, I have never yet seen anyone post that they have hand calculated on every fill-up and their onboard computer is accurate every time…

On the other hand, I have hand calculated every fill-up for 2 different trucks over a combined total of about 80K miles, and both trucks have been consistently high on what the onboard computer said. Every now and then the onboard is correct. And, I think 2, or maybe 3, times I actually got better than what the onboard said.

I use fuelly, and I agree.. the LOM (Lie-O-Meter) is almost alway optimistic by a decent amount.

 

[BowDown]

Maybe I'm missing the point to some of these observations, but are people really that concerned that their truck's mpg calculations are 1 mpg off? Even at 2 mpg off, are people driving their tanks low enough that it becomes a issue? Not trying to be d***, just trying to understand

I wouldn't be concerned by up to 1-1.5 mpg difference by the computer, my only point is that mine doesn't appear to be off by much if at all. I wonder why/if others are.