I am confused about my cars low MPG?
Posted by manbat_batman0913@reddit | askcarguys | View on Reddit | 72 comments
I’ve got a 2008 Jeep Grand Cherokee Laredo and I’m trying to figure out if my MPG is actually bad or if it’s just because of how I drive.
When I got it a couple months ago, the MPG was around 14.7. The highest I’ve seen it get was 15.1. I got the oil changed about 2 months ago and recently had the water pump replaced. Besides that, my mechanic said everything looked good, though I do think I may need to get my brakes checked soon. Lately though, my MPG dropped down to around 13.3. It’s back up to 13.4 now after I stopped idling as much, but I’m not sure how accurate that reading really is. I do a lot of short trips, and my drive to work is about 30–40 minutes each way with some highway but also a lot of stop-and-go traffic. I’ll be honest too—I’m still pretty new to driving and I definitely have a heavier foot with accelerating and braking than I probably should. I was also doing a lot of serious idling for a while—sometimes sitting in the car for 30 minutes to an hour just listening to music with the engine running. A 30–40 minute drive to work and back can sometimes feel like it takes close to a quarter tank, which seems kind of crazy to me. Does this sound normal for a 2008 Jeep Grand Cherokee Laredo, or does it sound like there could actually be something wrong with the vehicle causing the low MPG? Just trying to figure out if this is mostly my driving habits or if I should be looking harder for a mechanical issue.
Gringuin007@reddit
My buddy had this car. Like a 2006 v8 loaded. He said he got 8 mpg
kaneuens@reddit
Coasting and minimizing braking will help as well.
kaneuens@reddit
And make sure your tires are properly inflated
joker_1173@reddit
Way back in 2005 I bought one of the 1st SRT8 jeeps to come out, got a lot of modding done for free (the companies needed a test vehicle) after all was said and done - even driving moderately, I got 9 mpg
CartierWlayvo@reddit
jeep & dodge probably have the worst MPG lol u
AgonizingGasPains@reddit
It's not the vehicle. I never got more than 19 in either of ours, and that was highway, steady-state driving.
fakesocialmedia@reddit
You just explained it. City driving + heavy foot + heavy SUV = bad MPG. Their rated MPG was like 15-17MPG MAX anyway so there’s literally nothing you can do to fix it even if you coasted and did long drives, it’s just not a MPG friendly car in general
Equal-Fee770@reddit
A brief internet search says the 6 cyl is rated at 15 city 19 highway, and the 8 cyl is rated for 14 city 19 highway
fakesocialmedia@reddit
So.. just as bad, thanks
Equal-Fee770@reddit
17-19 makes a huge difference. And you said “like 15-17 MPG MAX” with authority. They may be capable of 22-24 on a long highway road trip.
fakesocialmedia@reddit
17-19 does absolutely nothing when it comes to sitting in traffic and having a heavy foot. You’ll never see that with the way the OP drives, and “may be capable” sure.. I’d love to see someone try
Equal-Fee770@reddit
My buddy got 25 going from Allentown Pa to pidgeon forge Tennessee. His was older though. A 2001 jeep grand Cherokee limited. Had the famed 4.0 straight 6 in it.
17-19 if it’s an 18 gallon gas tank is about a 50 mile difference. That might be how one gets to the next paycheck to fill up.
dontworryitsme4real@reddit
I think the only way you could get better gas mileage out of it is by buying another car and then towing the Jeep.
JSTootell@reddit
Does the duck go in the jeep, or in the tow vehicle?
titanicdiamond@reddit
Also, the fuel mix was just changed to E15 as a result of the Iran War. This will result in slightly lower overall MPG.
Occams_RZR900@reddit
They’ve only started to add E15 as another option for fuel. Gas stations will still have regular E10 in addition to E15.
titanicdiamond@reddit
Ope dumb me. Owning an EV only gets you off your fuel game.
Substantial_Team6751@reddit
Adjustment:
City driving + heavy foot + heavy SUV + (idling listening to music )= bad MPG
Ok-Office1370@reddit
I've always gotten significantly better mpg than listed on my cars because fhe average person apparently drives like you want to die so I'm more efficient than average. Note that this only happens after a few years. There is a break-in and maintenance period where cars hit their stride.
But you're not likely to get more than 10-20% away from the car's listed mpg either way no matter what you do.
The best way to improve your mpg as a Jeep driver, is stop being a Jeep driver. Mentally and actually. Get something else and don't be that person.
Jeep drivers in my area are notably awful. I've had Jeep drivers threaten me and cut me off and try to drive me in the ditch two different times, by two different Jeeps, in recent years, in a small community where I'm sure you'd all say that sort of thing doesn't happen.
BigQuick5150@reddit
The 4.0 in-line 6 is a great engine
TrainingChipmunk3023@reddit
Was.... the production line machinery and patents were sold off to a Chinese company before 2008...
BigQuick5150@reddit
I thought they just quit using it. Switched to some v6
TrainingChipmunk3023@reddit
They went onto 3.5 and 3.7 V6 motors for emissions and shorter or smaller engine compartments.
Bulky_Employ_4259@reddit
You have a big honkin’ SUV, you’re not yet an efficient driver, you see a lot of stop and go traffic, and you idle a lot. Unfortunately you’re gonna use a ton of fuel that way.
Don’t isle unnecessarily, running a whole ass engine just to power some speakers is not an efficient use of resources. Your driving will naturally get better with practice but also read up on efficient driving methods. You’ll see an improvement but that car will never be efficient around town.
No_Pen_376@reddit
haha!! really??
SevroAuShitTalker@reddit
A 20 year old jeep doesnt get good mileage? Im shocked
murphydcat@reddit
I'm amazed a 20 year old Jeep is still running!
CommonBubba@reddit
The 20-year-old ones probably run better than the two-year-old ones…
Slow_S60_@reddit
Na those jeeps were some of the worst
Inner_Pipe6540@reddit
Make sure your tire pressure is where it should be and check your air filter jeeps get lousy gas mileage anyways but the way you drive also affects it big time
Due_Attention_4886@reddit
I had a 2006 and I always got about 17-19.5 MPG when I was mostly doing highway driving. I probably got 16-17 MPG when I was doing more city driving. Constant start/stops with strong acceleration is going to have an impact. Are you someplace high-altitude like Denver? That could reduce efficiency by 1-2 MPG probably. Do you have normal tires or big knobby tires? Big tires will reduce fuel economy too.
JuanTheMower@reddit
1 to 2 mpg makes no difference in the grand scheme of things and doesn’t change the fact that you’re driving a largely inefficient vehicle.
FledglingNonCon@reddit
The difference between 14mpg and 16 mpg can be ~$400 a year, which isn't nothing, especially if all you can afford is a 19 year old Stellantis product.
durango_unchained@reddit
in 2008, jeep would not yet be owned by stellantis
FledglingNonCon@reddit
Yes, Jeep was run by FCA, which went bankrupt less than a year after this car was built and after being bailed out later merged to form Stellantis, by taking the worst American car company and combining with the worst European car company.
durango_unchained@reddit
a quick look at the Chrysler Wikipedia page will explain everything, including the FCA merger beginning in 2014 and ending in 2021 when stellantis took over.
ManKilledToDeath@reddit
Some are more concerned with getting a comment in ASAP than being correct lol
corsa180@reddit
There's no mechanical issue, it is all driving habits, and what you're driving.
Heavy SUV - check
City driving - check
Heavy foot - check
Idling for an hour - check
Ragnar-Wave9002@reddit
2008 Jeep Grand Cherokee Laredo
That's your problem.
I'm getting like 35+ MPG all day long in my small SUB hybrid.
NoPersimmon7434@reddit
That's silly. Your car can't fit passengers as comfortably, can't fit as much cargo, and can't tow much of trailer. A Grand Cherokee can go off-road in places you can't, and it generally handles rough terrain better. There are a plethora of reasons why a midsize SUV makes sense, and their Grand Cherokee is a much more capable vehicle than a small SUV.
Ragnar-Wave9002@reddit
90% of people in these things are in them alone.
I put 4 adults in my Ford Escape easily. And luggage. I've done weekends away with 3 people total in the car and all our shit.
Sorry, the car is 100% comfortable. Not sure why you think it can't fit 4 adults and you need a Grand Cherokee.
Off Roading? LOL. Ya, people do that all the time. And yes, I can drive down dirt roads like anyone else.
Handles rough terrain better? You mean faster the 2 times a year it matters. So all the extra cost to take a 5 minute drive down to 4 minutes. LOL.
I'll also put my beater up against that Grand Cherokeee any day and I don't complain about fuel economy when using it.
MountainFace2774@reddit
Everyone's situation is different. I manage perfectly fine in a 2-door Civic that gets 40 mpg when it's just me and one other person. A lot of the time now, I either have 2 adults and 2 carseats or 4 other grown men riding with me. The Civic doesn't go on those trips.
OP is a new driver. Not everyone can afford a new hybrid and depending on how many miles they're driving a year, they may never make up the extra fuel costs. A paid-off reliable vehicle that gets bad mpg is sometimes still cheaper than a car payment.
jrileyy229@reddit
Don't be confused, there's nothing you can do about it
TheTiltingKnight@reddit
Professional mexhanic and fellow jeep owner here, though mine is 10 years older. Welcome to the driving club, let me help you out a bit. Jeeps are not the most fuel efficient vehicles, but you can squeeze more miles out of each tank with the following tips.
First, stop using fuel with ethanol in it. It may be cheaper at the pump, but in the long run it costs more because it has significantly less energy per volume. Personally, I only use 91 ethanol free in all my vehicles and I gets me further between fill ups while taking better care of the engine.
Second, stop idling on purpose. Not only are you burning fuel, you are putting extra wear on the engine for no work completed.
Third, adjust your driving a bit. Quick to the speed limit isn't bad as long as you arent tailgating, try to hold smooth consistent throttle one up to speed. Next, stop racing to stop lights. Coasting is your friend.
Forth, if you have the option, take control of the transmission from the computer. Drive it like a manual, switching gears around 4k rpm. Not only will this help the engine burn more efficiently, it keeps you operating in the peak power band. This behavior limits begging and excess fuel consumption from delayed shifting by the computer.
From the maintenance standpoint you could probably use a tune up. Contrary to manufacture claims, spark plugs and thier associated coils can not in fact perform correctly for 100k miles. Depending on driving habits, spark plugs and coils stop producing peak spark after 25-30k miles, and continues to drop off sharply the longer they are run past that 25-30k mark, leaching mpg as it does it. Id recommend having your plugs and coils replaced to at least have a peak spark and go from there. Put all this together and you might be able to squeeze 18-22 highway or better. Stop and go city traffic is always going to be a fuel suck, but as long as you arent racing to stop lights you should improve fuel economy there too.
red18wrx@reddit
That's about what I would expect from something big, heavy, and with the drag coefficient of an air brake.
Mundane-Exercise6333@reddit
My 2020 and 2021 grand Cherokee averaged about 17mpg
TrainingChipmunk3023@reddit
Was....the whole production line machinery and patents were sold off to a Chinese company before 2008...
UnderwhelmingAF@reddit
Not sure what engine you have, but none of them were very fuel efficient. The EPA ratings were as follows:
3.7L V6: 15/19 city/hwy
4.7L V8: 14/19
5.7L V8: 13/18
3.0 V6 Diesel: 18/23
Given this and the age of the car, it’s probably about right.
RandomGuyDroppingIn@reddit
You get 0 MPGs sitting and idling (you're not moving), so yes sitting for extended time periods idling is going to use a lot of fuel.
Gradual take offs and stops will help tremendously with fuel. Most all vehicles get their absolute best air to fuel mixture so long as you don't exceed roughly \~2,500 RPMs accelerating. Air flow & fuel delivery have been tested across all makes and engine sizes, and it's right around the 2,500-2,800 RPM that is the sweet spot. Learn how to engine brake. Your engine is a very large pump, so if you simply let off the gas and coast as much as you can to a stop it'll help. Will also help with brake wear.
Your speed during your commute will also be a factor. MPGs see massive drops when you're driving \~75-80 MPH. You need to be in a 60-65 MPH range on interestates, and assuming your state highway speed limits are 55-60 MPH.
murphydcat@reddit
I owned a 2007 Grand Cherokee Laredo and that was my gas mileage as well. Mostly city driving. It was a big, heavy SUV. I wasn't expecting decent fuel economy.
NectarineNo4312@reddit
I notice that when I leave congested city streets and head out to more sparsely developed areas (not rural) my mpg improves about 20%. Seems vehicles don’t meet their stated “city” ratings in true city driving.
Forker1942@reddit
I had a guy at worked that drove 150 miles every weekend to his other house he drove as fast as possible 70-90. One weekend in the same lifted tundra, he had to tow. So he only drove 55. He was shocked the whole round trip even towing didn’t even use a tank of gas. He says it usually takes him a tank and a half.
No lessons were learned. Even if he saved an hour on the round trip he lost so much more having to work hours to pay that gas
Dry-Discipline-2525@reddit
MPG compared to average speed is a more useful metric than MPG by itself. That stop and go kills it and your numbers sound reasonable to me. Bad spark plugs can lower mpg so I would check those. Failing fuel filter and injectors can too but you'd probably be noticing other issues as well.
Pale-Ad6216@reddit
Also off road biased tires under inflated tires. And a fresh air filter. Any time I’m seeing my normal mileage dropping off, I change oil and filter, air filter, check plugs and confirm air pressure. Many of those are getting checked at regular intervals, but that is kind of my starting point for DIY stuff that can make a difference in observed mpg.
NecessaryEmployer488@reddit
Did you change gas? A mid-grade gas might bring the mileage back up. Are you driving less on the highway?
Sweaty_Illustrator14@reddit
We had a couple in our fleet. They got 10 mpg, burned 1-2 qts oil per tank, and was sin the shop every 3 months after 50k miles. Dodge Durango same experience.
LivingGhost371@reddit
What are you expecting to get? I had a 2004 with the V8 HO and I never got better than 17 even cruising on the highway. You can't compare an "old school" SUV with a huge engine to a modern crossover or something. n
wpmason@reddit
It is 100% the way you drive.
bobqzzi@reddit
That's brutal.
GetawayDriving@reddit
What is your expectation for gas mileage? The jeep is being a Jeep. You have a large SUV that’s known for being inefficient. It was inefficient when it was new, but now it has aged 20 years and become less efficient. You’re driving it with a heavy foot in traffic and you’re idling. 13mpg is pretty normal for a Jeep.
edwbuck@reddit
Your vehicle weights 4,500 lbs. Even a "heavy" sedan weights 3,200 lbs. You need more fuel to lug around the heavier car.
Your car is built to be a rather tall box with only a few modifications to attempt some aerodynamics. It likely has a coefficient of drag per area (CDA) between 12 and 14, based on other similar Jeep models. Most sedans have a CDA between 6 and 7.
Your car is built to tow 6,500 additional pounds, which mean permanent gearing changes in the transmission and drive train to always produce that power, even when you don't use it. Most cars can tow about 1,500 additional pounds
To make that massive brick of a car not drive like the slowest heaviest vehicle on the road, they kept increasing the engine size, to burn more gas, to provide more power till the car drove more-or-less like a sedan. And it got 15-17 when it was new. Now that it's not, it's getting 14.
In short, even if you could learn every driving trick in the book to save gas, you can't fix it. It made too many design choices that work against you. It's designed to get the crappy gas mileage you are getting.
Monster51915@reddit
That’s older vehicles in general for you let alone bigger vehicles.
Jack_ButterKnobbs@reddit
Most of it seems to be your driving style and the idling but a commonly overlooked factor is tire pressure. Id guess because its a jeep you have all terrain tires which arent great for MPG but a properly (or slightly overpressured) tire will improve mpg by 1/2 to 1 sometimes more.
jsaranczak@reddit
Jeeps aren't sold for their fuel efficiency.
MountainFace2774@reddit
You drive a gas hog in the least-ideal conditions. Depending on how much you drive in a year, it could potentially save you money in the long run to trade for a more efficient vehicle. You'd have to run the numbers to see if it made sense.
Kootsiak@reddit
Are you in the USA? I hear that they are going to start upping the amount of ethanol in the Regular 87 fuel in some places across the country, which will hurt MPG some, as will driving habits and conditions.
DoubleResponsible276@reddit
Bro listed all the ways how one might waste gas and is still questioning if something wrong. Yeah, bad driving habits.
H0SS_AGAINST@reddit
You didn't mention which engine you have but upon review, they all suck.
Whatever you do, please don't start acting like you lost your accelerator pedal. Now that we are back to 2022 gas prices I feel like I am constantly getting stuck behind people driving inherently inefficient vehicles taking a literal mile to accelerate to the speed limit.
JollyGreenGigantor@reddit
In stop and go traffic, try to keep moving at a slow speed rather than coming to a stop and accelerating up to speed. Like rather than going 0-40-0-30-0-40-0-25-0 try to cruise at 15mph.
Give more space to the cars in front and don't worry about the cars that end up moving into that space in front of you, they're not slowing you down in any meaningful way.
pdxsilverguy@reddit
6 cyl or V8?
happyjoyjo@reddit
Your mileage dropped 13%, that can happen for a variety of reasons. Heavy foot yes, could be more traffic, winter gas/higher ethanol. It's pretty normal.
Few things to check just in case though, -make sure your tires are full according to the sticker on the drivers doorwell. -Old spark plugs will cause a drop in mileage. Might not throw a check engine light even. -Stuck brakes or other maintenance items not up to snuff. -try to be easier on the throttle and it'll save you a few bucks on fuel and maintenance in the long run.
Also if you're concerned about gas mileage maybe don't drive a 5.7L V8 SUV. They're not meant to get good gas mileage. You'd spend about half as much if you were in a sedan.
Best of luck though 👍
Ancient_Narwhal_9524@reddit
If you are idling for long periods of time you are just eating gas and lowering your MPG.
The MPG shown by the car is also slightly optimistic in my experience. You will get a more accurate reading by tracking actual miles driven vs gas used.