[jdr30]

Bought an off-lease 2017 Frontier SV with about 23K miles on it. Window sticker showed 19/23 gas mileage. I figured that was high but 16/20 would have been acceptable. I travel 45 miles each way, 90% highway, Monday - Friday. I am lucky if I get 13MPG highway. And what's ironic, is the mileage is MUCH better when I am moving around the city. It jumps up to about 16MPG.

Because of this I have to fill up every other morning. I am unfortunately regretting this purchase. I never expected mileage to be this bad. And just for the record I have

1. Good tires, filled to recommended PSI
2. Air tight cover on tailgate to reduce drag
3. I am NOT locked on 4WD
4. I do NOT have a lead foot
5. Air filter is good

One more thing. This thing has a 21 Gallon tank? I notice once the light comes on, even if I drive it until the line is basically lined up with the E and I fill it up I never fill up more than 16 gallons. So even with the line on EMPTY this thing still has 5 gallons of reserve??

Any suggestions or tips?

Thanks in Advance.

 

[shift_RUSH]

You might have your cats/exhaust system's flow checked? Have read that even just checking the LvsR cat temp w/ an IR thermometer can yield some useful data.

Otherwise, interstate speeds of 75+ don't yield ideal hwy MPGs...where speeds of 50-65 will do much better.
~ I'll get 16 at 80mph...and have gotten nearly 22 at 60-65...both are hand calculated.

Yep, 21.1 gal tank. Learn where your true 1/2 tank full/empty is using your hand computed MPGs and you'll learn a lot about how your gauge performs. My true half tank is just North of 3/8s full.
When my low fuel light comes on I can generally only put in ~17 gallons...others are +/- from here.

Otherwise, put gas in it and drive it. It's a truck. Having said this, I've tracked every tank of gas in mine cuz I want to know if/when there's a problem. If your truck has a problem, I hope you get it sorted. As stated above, I'd start w/ the exhaust/emissions system.

 

[Clint]

I’m surprised at your results, I have driven so many highway miles and saw as high as 23 mpg on a straight highway tank multiple times. I’d have to go find my old window stickers as I don’t believe the mileage numbers you stated were correct, I’m thinking 15-21 was on my stickers.
I’ve pulled a utility trailer from NJ to Florida and back and got 18 mpg on the highway. What tires are on the truck, some have installed load range E, they weigh more and create their own issues.
There are many variables but after owning four 4.0 engines, all got better results than you’re stating.
something isn’t adding up. Hope it can change for you.

Clint

 

[SoCal]

Bought an off-lease 2017 Frontier SV with about 23K miles on it. Window sticker showed 19/23 gas mileage. I figured that was high but 16/20 would have been acceptable. I travel 45 miles each way, 90% highway, Monday - Friday. I am lucky if I get 13MPG highway. And what's ironic, is the mileage is MUCH better when I am moving around the city. It jumps up to about 16MPG.

Because of this I have to fill up every other morning. I am unfortunately regretting this purchase. I never expected mileage to be this bad. And just for the record I have

1. Good tires, filled to recommended PSI
2. Air tight cover on tailgate to reduce drag
3. I am NOT locked on 4WD
4. I do NOT have a lead foot
5. Air filter is good

One more thing. This thing has a 21 Gallon tank? I notice once the light comes on, even if I drive it until the line is basically lined up with the E and I fill it up I never fill up more than 16 gallons. So even with the line on EMPTY this thing still has 5 gallons of reserve??

Any suggestions or tips?

Thanks in Advance.

If your state uses ethanol blended gas, your mileage will suffer. I’m in California and my truck gas mileage is close to yours - but my driving is mostly short trips around town.

 

[RamTest]

Disconnect your battery for 15-20 minutes to let all of the modules reset.
Be sure the battery posts and cable terminals are as clean as new. Use a battery brush.

 

[woodtemple]

Also use cruise control as much as possible/where safe to maximize fuel economy.

 

[jdr30]

If your state uses ethanol blended gas, your mileage will suffer. I’m in California and my truck gas mileage is close to yours - but my driving is mostly short trips around town.

yeah, I am in New Jersey

 

[RockMechanic]

I'm going to go out on a limb, have you tried different gas stations? Because if your always getting from the same company they may not have the best quality?

Like I said, shot in the dark.

Another highly unlikely but honestly more likely than my fringe science first idea is a bad PCV valve. I've had issues with dealerships using really low quality oil around here, if they put el cheapo's regular oil in and did changes on the 6000 mark the old oil could of clogged the valve. There is nothing that will kill mileage faster than a failed PCV valve because it will cause the engine to think its running lean and it will add fuel to compensate.

 

[jdr30]

I'm going to go out on a limb, have you tried different gas stations? Because if your always getting from the same company they may not have the best quality?

Like I said, shot in the dark.

Another highly unlikely but honestly more likely than my fringe science first idea is a bad PCV valve. I've had issues with dealerships using really low quality oil around here, if they put el cheapo's regular oil in and did changes on the 6000 mark the old oil could of clogged the valve. There is nothing that will kill mileage faster than a failed PCV valve because it will cause the engine to think its running lean and it will add fuel to compensate.

I don't always go to the same gas station but I always get REGULAR.

 

[IAm_Not_Lost]

Just to check, because I don’t think I saw anyone mention this....

you are calculating your gas mileage by hand correct? Filling the gas tank up completely and resetting odometer, and then when you fill up again dividing the amount of miles traveled on the odometer by the amount of gallons put in. If you are just going off the computer that is horrendously inaccurate.

Yes, our tanks are 21 gallons, and yes when the empty light comes on you have about 4-5 gallons left. I can usually get about 250ish miles before my empty light comes on.

realistic gas mileage with these trucks is about 15-16 in town, 17-20 on highway with conservative driving. This is assuming no mods that kill mpg like lifts, bigger tires, removing air dam, adding roof rack stuff.

 

[SoCal]

I'm going to go out on a limb, have you tried different gas stations? Because if your always getting from the same company they may not have the best quality?

Like I said, shot in the dark.

Another highly unlikely but honestly more likely than my fringe science first idea is a bad PCV valve. I've had issues with dealerships using really low quality oil around here, if they put el cheapo's regular oil in and did changes on the 6000 mark the old oil could of clogged the valve. There is nothing that will kill mileage faster than a failed PCV valve because it will cause the engine to think its running lean and it will add fuel to compensate.

I do always go to the same gas station, but is a well known brand “ARCO.”
My truck has 3600 miles on it, and is just over a year old. My last truck was a 2017 Frontier 4 cylinder with 7500 miles - and it was nearly as bad. I think it’s the gas sold in this state, but I am going to try another brand in case that’s an issue.

 

[RockMechanic]

I don't always go to the same gas station but I always get REGULAR.

There should be no need to get anything other than regular. Well that covers that one far reaching limb of the tree.
Do you have any information on the service intervals before you got the truck? I wonder if there's a mismatch of the Leese's time with it, and the maintenance. There isn't a lot that could of happened in that amount of time outside of someone having never changed the oil, until right before you got it.

 

[shift_RUSH]

For a 3-4 yr old truck w/ only 23k miles, I doubt it's your PCV valve. But replacing is cheap, yet quite inconvenient...and is especially useful/advised for when an engine is burning some oil. Of course, there's other reasons for burning oil, but will leave that to a different thread.

 

[shift_RUSH]

Higher octane &/or ethanol &/or ethanol free has proven to only lighten my wallet. No gain in fuel economy in all my testings.

 

[RockMechanic]

Higher octane &/or ethanol &/or ethanol free has proven to only lighten my wallet. No gain in fuel economy in all my testings.

My truck was a bit rough/loud when I first got it, had the idea to try premium, it quieted it right down, ran that for the first 2.5-3k miles and after that It was good. Definitely would do again/recommend for the break in period of a new vehicle.

Back to the topic, if the maintenance ends up all checking out then it's got to be the route your driving, some areas may look totally flat but actually be a significant long flat hill. Take a look at your average rpm when your driving should average from 1250-2500 for most of your driving. Also Traffic kills mileage.

 

[CT_Nismo]

Your mpg of 13 mpg on the highway is deep in the tail of the bell curve. But there have been other owners who reported this type of number and all have stock units. Make sure your parking brake is completely off. The test I would use is to find a secluded downhill road. Get it going and then shift to neutal. Apply the parking brake. It should take no less than 4 clicks before you feel drag.

However your 16 mpg in-town is quite acceptable in winter driving.

 

[invasion08]

Also depending on where you live, gas stations may have winter blend fuel. Winter blend fuel will lower your mpg.

 

[bajasam]

Download a copy of the 2016(same as 2017) Svc manual Chptr EC, read it thru and preform all the fuel injection-throttle body relearn procedures 4 I think and try going thru all of them,possible that re-calibrating your system could help you a little.Doesn't cost you anything to try.

 

[bagwell]

since you're rightly concerned - I'd get an alignment, change the oil & filter (5w-30 with OEM filter), even if the dealer says they changed it or it shows clean - easy to do yourself and verify the correct oil weight is in there.

 

[Iffin'itaintbroke]

My truck is a 17 sv cc lwb. Lifted, load range E tires, no air dam. I only run Shell 89 octane. I do occasionally drive in a "spirited" manner but not often. I average 16.5 to 18 mpg in mixed use. Highway with the cruise at 68 mph I get about 21.5, depending on my load. And that's in hilly New England. Got 15ish running 80mph through W Virginia...

When I got my truck it was off lease. Had a rough idle, especially with the AC on. Fuel mileage was bad also, about 13 average. Within the first 1,000 miles of my ownership I changed my plugs, oil/filter, cleaned my throttle body, cleaned my mass air flow sensor, installed a drop in K&N and did the throttle body relearn after all was completed.

It smoothed the idle right out and increased it's response as well. My fuel mileage then was 18.5+ around town, 22.5+ on the highway. But that was before any kind of mod.

The plugs that came out were toast, completely junk. And that was at 19k, can't imagine how bad they'd be now had I left them in. Also, the throttle body was caked in burnt on oil.

You have no idea how poorly people will treat their vehicles. Take a look at the above items, you may be surprised. If the previous owner used sh it oil and sh it gas and more than likely ran it hard as well, you'll find evidence of it.

Don't expect a miracle though, these trucks have a drinking problem. Best we can do is get them to guzzle less. Good luck!