Gas Mileage

[Dodge Lover]

I recently purchased a used 1500 SLT 4x4 with 5.7L Hemi, 8 sped trans and 3.21 rear end. According to the VIN I should be getting 21MPG Highway, 15MPG City and 17 combined. My first couple weeks have averaged 10.4 to 10.9. Is this normal? TIA!

 

[kurek]

I recently purchased a used 1500 SLT 4x4 with 5.7L Hemi, 8 sped trans and 3.21 rear end. According to the VIN I should be getting 21MPG Highway, 15MPG City and 17 combined. My first couple weeks have averaged 10.4 to 10.9. Is this normal? TIA!

There are three different things happening here... first is that what you should be getting is a bit misleading because everyone has different factors affecting their mileage like traffic, mountains, individual driving style, if the truck has been modified (lifted, big tires, etc), all sorts of stuff. But those numbers (21 highway, 15 city) are pretty realistic for a stock truck like you described if you're a pretty average driver.

Second is that the EVIC (instrument cluster display) is really just an estimate and it can't do its job if it's getting bad information - in particular if somebody installed differently sized tires and didn't recalibrate the truck for those tires. Tire size calibration affects not only the EVIC mileage calculation but also engine and transmission controls so a miscalibrated truck will not deliver optimum fuel efficiency nor report it accurately. I'm just assuming that the MPG numbers you've got so far are from that display.

Third is that 10mpg is unusual and shouldn't be happening on a truck that's in good shape, and is outside the bounds of what could just be explained by normal driving behavior unless you're just mashing the throttle everywhere you go and rolling along in rush hour traffic stop and go continually.

Two things you can do - first verify whether the truck is modified and whether those modifications are affecting mpg, second verify that your mileage estimates are accurate by hand calculating distance vs. fuel use, the old fashioned way and see if that gives you a different number than the dashboard display.

 

[CamperMike]

If you're driving in town stop and go it can be pretty low. Highway at 60-65 should be over 20. Highway at 75 high teens. I get around 13-15 in mixed driving. Towing get 8-9

 

[Dodge Lover]

The tires are stock size. No mods have been done that I'm aware of. I AM getting my info from the EVIC. However, I drove about 160 miles round trip, mostly on the freeway and used over half a 26 gallon tank.

I've only owned it a couple of weeks. I'm taking it back to the dealer to have it checked out. Hopefully it's some thing as simple as a software update.

 

[NJMOPAR]

I did a 132 mile round trip on mostly highway today avg 80mph w/AC on and used 1/4 tank (32gal tank)
This is a 2010 w/127k and a bunch of mods.

Around town I'm always punching it and get 8-10.

 

[Bigskyroadglide]

Op you didn't provide number of miles on vehicle, or model year or type of fuel you are running.

I can only assume you must have a 14 or later truck, with the 8 sp and 3.21.
In addition if miles are under 100k, then it's probably not plugs, if over 100. It could be.

Last if your pumping 87 octane, and it contains ethanol then that affects mileage at well.

I have a 16, 5.7 Laramie with 8sp and 3.21. On 87 octane ethanol gas it will average 14 around town. On 89 real gas (non ethanol) it will easily get 16.5.

On trips, consistent 18 to 19 mpg.

I'd say you should experiment a bit, before you make it a dealer issue. The type of gas, octane, mileage tire pressure and oil type (Dino or synthetic) make a difference in mpg

 

[kurek]

I'm able to get 20mpg when I try - highway, but realistic - with a 6 speed, 3.55 geared 4x4 on all E-rated all terrain tires with a lift and aftermarket bumper (no air dam)... burning E10. I don't think I could average less than 15 in the town I live in without breaking some sort of a law in the process, just not enough stop and go traffic for that.

If 10% of your fuel has ~27% fewer BTU's at worst it could mean 3% fewer mpg

 

[Bigskyroadglide]

I'm able to get 20mpg when I try - highway, but realistic - with a 6 speed, 3.55 geared 4x4 on all E-rated all terrain tires with a lift and aftermarket bumper (no air dam)... burning E10. I don't think I could average less than 15 in the town I live in without breaking some sort of a law in the process, just not enough stop and go traffic for that.

If 10% of your fuel has ~27% fewer BTU's at worst it could mean 3% fewer mpg's. I know hating corn sauce is a religion and nobody's mind is going to get changed but at least we can stick to facts when they're readily available.

I don't hate corn, but my ram sure does and so does my wallet. Regardless of the math, my real world experience has proven that in my ram i get less mpg with ethanol gas. And a fact, by definition is something that has been proven to be true. So I'll continue to pump real gas when I can find it cause I can and I get better mpg.

 

[jws123]

2011 ram 210k 87 octane 11-12 around town parkway i can get 17 ish its only a 5 speed and has others have said evic is never that accurate. Also is mds enabled? iI found with mine before I removed it I kept giving it gas to get the truck to maintain speed on highways hence wasting more gas mpg went up when I removed it drives better to ahahah.

 

[Dodge Lover]

Op you didn't provide number of miles on vehicle, or model year or type of fuel you are running.

I can only assume you must have a 14 or later truck, with the 8 sp and 3.21.
In addition if miles are under 100k, then it's probably not plugs, if over 100. It could be.

Last if your pumping 87 octane, and it contains ethanol then that affects mileage at well.

I have a 16, 5.7 Laramie with 8sp and 3.21. On 87 octane ethanol gas it will average 14 around town. On 89 real gas (non ethanol) it will easily get 16.5.

On trips, consistent 18 to 19 mpg.

I'd say you should experiment a bit, before you make it a dealer issue. The type of gas, octane, mileage tire pressure and oil type (Dino or synthetic) make a difference in mpg

I didn't post the model year as it's in my info to the right of my post. It's a 2013 with 118,000. I'm running regular as I didn't know it was supposed to be mid-grade. Oregon has 10% ethanol. The only way to get around that is $4+ per gallon 92 octane Premium normally used in lawn equipment, etc. When I bought it they sold me Synthetic Life time oil change package. I'm assuming that's what's in it. I'm taking it to the dealer because it was sold to me that way and I believe it's their responsibility to fix any problem they might find, without cost.

 

[Dodge Lover]

2011 ram 210k 87 octane 11-12 around town parkway i can get 17 ish its only a 5 speed and has others have said evic is never that accurate. Also is mds enabled? iI found with mine before I removed it I kept giving it gas to get the truck to maintain speed on highways hence wasting more gas mpg went up when I removed it drives better to ahahah.

I heard you can just shut the MDS off.

 

[indept]

The only way to shut the MDS off without a custom tune is to use the manual shift buttons & set it to 8th gear ( which is the max gear it will shift to) or set it to tow haul mode. You will have to do one of the above each time you start the engine if you want it disabled. MDS doesn't bother me. Some here don't like the sound it makes when running on 4 cylinders.

 

[retired]

An almost 9 year old truck with 118,000 miles…good luck with the dealer doing anything. Maybe your brakes are dragging.

 

[jws123]

I heard you can just shut the MDS off.

You can but i wiped my cam out year or so ago so i removed it all and disabled it with a tuner.

 

[NJMOPAR]

Tow/haul will not disable MDS, it just changes the shift points in the trans.
Only the +/- buttons will temporarily disable it.
Tuner permanently does.
And the ECO light doesn't mean MDS is active, it's just letting you know you're driving easier & saving gas.

 

[WireEd]

I don't hate corn, but my ram sure does and so does my wallet. Regardless of the math, my real world experience has proven that in my ram i get less mpg with ethanol gas. And a fact, by definition is something that has been proven to be true. So I'll continue to pump real gas when I can find it cause I can and I get better mpg.

Bigsky you are spot on. Most of the fuel that we use contains ethanol. Ethanol burns cleaner than gasoline but is less efficient. It's only 66% as efficient as gasoline. You can calculate the percentage drop of the corn infused gasoline but basically you are going to drop 2-3 mpg when using the 90/10 mix. You get better mileage with ethanol-free but at higher price.

 

[kurek]

If your vehicle gets 14-17% fewer miles per gallon from a fuel which has 3% fewer BTU's there is something wrong with your engine.

I'm still amazed by how much superstition persists about the most common fuel in America.



Ram 1500 395hp at 5600 rpm

Estimate 450cfm (80% VE)

Mass of 450 cubic feet of air 36.3 lb

Mass of petroleum gasoline at 14.7:1 air/fuel ratio 2.47 lb
Mass of pure ethanol at 9:1 air/fuel ratio 4.03 lb

Energy content in 1 gallon reference petroleum gasoline 114000 BTU
Weight of petroleum gasoline 6.25 lb/gallon
Energy content in 1 pound reference petroleum gasoline 18240 BTU
Energy content in 2.47lb reference petroleum gasoline 45053 BTU



Energy content in 1 gallon pure ethanol 76330
Weight of ethanol 6.53lb/gallon
Energy content in 1 pound pure ethanol 11689 BTU
Energy content in 4.03lb pure ethanol 47107 BTU (4.56% increase vs. pure petroleum)


Energy content in 1 gallon E10 reference same numbers above, (114000 x .9) + (76330 x .1) = 110233 BTU
Stoichiometric AFR for E10 (14.7 x 0.90) + (9.00 x 0.10) = 14.13
Weight of E10 6.278 lb/gallon
Energy content in 1 pound of E10 17559 BTU
Mass of E10 at 14.13 AFR 2.57 lb
Energy content in 2.57 lb E10 45126 BTU (0.162% increase vs. pure petroleum)

 

[MRFREEZE57]

gas mileage can vary from so many things. does your truck seem to be running normal and have good power? in combined driving I get around 17mpg with 3.92 gears, all start and stop would guess would get no better than about 13.

 

[Bigskyroadglide]

So, I have 4 5.7 hemis.

A 11, 5.7 quad cab 4x4 6 sp, 3.55s
A 14 5.7, RCSB, supercharger, RWD, 8 speed, 3.92s
A 15, 5.7 8 speed, AWD Durango
A 16 5.7, 8 speed 4x4 quad cab 3.21s

So I have more than 1 data point.

My 11, 150k miles, original engine, updated coils, iridium plugs, avg 18 mpg highway. 15 in town
Real gas, drops ~2 mpg if it's ethanol.

My 14, 47k, supercharger avg 25 mpg highway, 20 in town. Ethanol numbers, I have not changed plugs nor run Real gas in this truck. Not really comparable.

My 15, AWD, 18 highway, 13 around town. It's a Durango RT, smaller lighter and not comparable to trucks. Real gas it will avg 23 highway and 16 around town

My 16, 5.7 Laramie with 8sp and 3.21. On 87 octane ethanol gas it will average 14 around town. On 89 real gas (non ethanol) it will easily get 16.5.

On trips, consistent 18 to 19 mpg even the occasional 20 if I not pushing low 90s.

I average driving 50K a year, in mileage. So fuel economy is a thought. Cost per mile is about the same as ethanol vs real gas due to the real gas premium, but fuel economy and power are different.

 

[David James]

2016 1500 4wd crew cab, 5.7, 3.21, 75k miles, 20” highway tires, 5w20 synthetic on 5k change. Mileage typically 20-23 mpg on highway 65-75 mph speeds using cruise as much as possible. Town 16-18 mpg. Drive gently.