How I got 23 MPG in my 1999.5 QX4

[gwhunt23]

Hope that topic title caught your attention. : Achieved 22.7MPG today in mixed country roads / interstate driving in my 99.5 QX4 with the VG33 engine.

Basically I've been slowly searching for down-to-earth ways to increase my gas mileage in my QX4. Here's what I've done, hopefully you can read through this list and say "Ooohh that would be a good idea!" to at least some of the ideas.

MECHANICAL1) Clean air filter. Personally, I use just an ACDelco paper air filter. 2) Clean fuel filter. Just changed mine, used a Purolator from Advanced Auto Parts.3) New spark plugs. NGK V-Power. Cost less than the stock NGK model, but the NGK website claims that the V-Power series improves fuel economy.4) Full synthetic 5W-30 engine oil. The Wal-Mart brand seems to be fine. 5) New O2 sensors. I got the codes to replace 2 of them, so the rear 2 are new, front 2 are stock. 6) New coolant temp sensor. It was a $20 part, not sure if changing it really did improve fuel economy but it definitely didn't hurt. 7) Up to date on all other fluid changes (differentials, transmission, transfer case)

PHYSICAL1) I tow all my toys instead of putting anything on the roof. So, I took off the roof rack crossbars, the tie down bars, and the sunroof wind deflector. It looks fine. I left the rear window deflector on because it looks ridiculous without it. 2) Tire pressure. I make sure they're always inflated to 26PSI when cold, just as the inside door jamb recommends for my stock size tires. 3) 2WD mode. Don't stay in Auto if you don't have to. 4) Run the AC at highway speeds. It's much more fuel efficient to run the AC than to have the windows down, creating more drag. 5) If it's cold enough to have the heat on outside, use "ECON" mode on the digital climate control. If it's on auto the AC compressor will still run as AUTO heat includes auto defrost. 6) Gasoline: I run standard 87 Octane from Sheetz whenever possible. Nothing fancy. They just always have the cheapest prices around here.

Even with all of this, the best way for me to increase fuel economy was to slow down to the speed limit and drive in the right lane all day. It's a much less stressful drive and your fuel economy will shoot through the roof.

I also try to keep shift points as low as possible. Anything over 3000rpm is too hurtful to gas mileage.

For in town driving, when I see a red light, I immediately let full off the gas and coast the rest of the way to the light. Many traffic lights are timed in a series to make speeders stop. So, if you coast up to a red light on a day with little traffic, chances are the light will turn green and you'll be able to cruise right on through, saving gas AND getting to your destination quicker than if you were to stop!

Good luck and God bless!

[Qxxx4]

great tips! thanks for your info and 22MPG is unheard of in this forum good to hear its possible

[bustarye]

how hard is it to replace the O2 sensors??

[BoroBrown]

Yeah i am in the process of trying the same thing except i just went w/ an oil change and tire pressure. (BTW i have heard if you inflate 2psi over recomended you can get another 1-2 mpg) And i have been driving like a granny and i haven't filld up again yet but just looking at my gauge i can tell a difference. I used to get about 60 miles to the first 1/4 tank this time i got about 95 so that is a 50% increase which i am very happy about. so if i can get between 20 - 25mpg i may not have to but a civic for school. The real test will be this comming weekend. when i will be driving to Nags Head interstate all the way. setting cruise a 60 and going. I have heard 60 mph is where you get the best gas milage and they say for every 5 mph over it is like paying .20c/gal more. Will update when i fill up.

[Mr Nice]

MECHANICAL1) reduces the chances of engine leaning out, so theoretically will decrease fuel economy compared to a dirty filter2) same as above5) downstream O2 sensors have nothing to do with the engine or the fuel system. all they do is monitor efficiency of the catalytic converters6) actually it could hurt. if your cooling system was running slightly hotter (due to a faulty CTS), it would be burning more efficiently than a cooling system with a CTS in good working condition

PHYSICAL2) it wouldn't hurt to inflate them to 32-35psi cold. you'd get even better fuel economy, at the expense of a slightly (if even) more harsh ride.4) the differential is questionable, at best6) running lesser quality (more additives) gasoline will actually hurt your fuel economy. the fuel costs may go down slightly, but not enough to negate any loss in fuel economy

[SnowSurfLax]

I got 22mpg once, pure freeway w/ cruise control.

The OM says it's more fuel efficient to drive with the AC on than to have the windows open.

A slightly hotter engine will not necessarily increase efficiency.

Higher tire pressure will give you better MPG but a stiffer ride. Softer tires absorb more of the small bumps but lay down more tire increasing your rolling resistance. Less tire means lower rolling resistance. Not enough tire can result in lost of handling and/or blown tire. So never go over 5 psi (cold) than what is recommended on the side of the tire.

[alexf20c]

A slightly hotter engine will not necessarily increase efficiency.

depending on the normal operating temperature of the engine (set by the OE thermostat), a hotter engine can very well burn furl more efficiently. i'm not saying that you should overheat your car to save fuel; just that the OP's claim that "it definitely didn't hurt" is not true.

Higher tire pressure will give you better MPG but a stiffer ride. Softer tires absorb more of the small bumps but lay down more tire increasing your rolling resistance. Less tire means lower rolling resistance. Not enough tire can result in lost of handling and/or blown tire. So never go over 5 psi (cold) than what is recommended on the side of the tire.

haha, are you again just pulling this stuff out of your ***? going 10psi over OE recommendation (to an EARTH-SHATTERING THIRTY FIVE psi) will not hurt your handling as much as much more minor changes to the car's suspension/wheels/tires. if going 9psi over was dangerous, then may God be with those that put non-OE size tires on their vehicles, because it's a death wish!

any tire that can realistically fit (or be fitted on) a pathfinder will have a load rating more than enough to handle 35psi cold, even with maximum payload.

[KoukiS14]

I hit 16 once on the interstate and I was stoked. My unwillingness to slow down and make other compromises led to the demise of my QX4, however

[ubpsanity]

Whatever you do to increase your fuel effiency, just don't go and get a Scangauge :-) If you do that, you'll be constantly watching it to see what works best...

Playing the fuel numbers game...

You can see in real time what speed works best for you. Whether or not it's best to idle down a hill or accelerate down the hill to coast up the next hill.. Whether to place it in neutral or leave it in gear when coasting to a stop (the answer to that one may surprise you)....

it's actually a good idea, I'd say I've paid for the purchase price in fuel savings, and with fuel pushing $1.30/L (about 5.20 per gallon) here, it'll pay itself off faster. I'd say I regularly get about 22MPG now, and all because of the Scangauge

[SnowSurfLax]

haha, are you again just pulling this stuff out of your ***? going 10psi over OE recommendation (to an EARTH-SHATTERING THIRTY FIVE psi) will not hurt your handling as much as much more minor changes to the car's suspension/wheels/tires. if going 9psi over was dangerous, then may God be with those that put non-OE size tires on their vehicles, because it's a death wish!

any tire that can realistically fit (or be fitted on) a pathfinder will have a load rating more than enough to handle 35psi cold, even with maximum payload.

At what point did I even mention OE? I think I said:

So never go over 5 psi (cold) than what is recommended on the side of the tire.

So, not what's listed on the sticker on the car, but what's inscribed on the side of the tire. Mine say 35 max psi, I usually run it up to 40 for daily driving.

You can run it higher, but I was stating 5psi over as a general guideline for the average user. A lot of people who cruise through our forum usually don't know a lot of cars and are just looking for some advice. Those who do know would normally just ignore it and do whatever they think is best for them.

haha, are you again just pulling this stuff out of your ***?

No need for personal attacks either. We're all friendly here.

[fueler]

You can see in real time what speed works best for you. Whether or not it's best to idle down a hill or accelerate down the hill to coast up the next hill.. Whether to place it in neutral or leave it in gear when coasting to a stop (the answer to that one may surprise you)....

Post up tyhe answer. I'm interested. I'm guessing leave it in gear and let the engine slow the car down, in gear (zero throttle). I know that in my Honda, doing so shuts down the injectors completely, whereas putting it in neutral still sends fuel through the injectors and technically uses more gas to keep the engine running in neutral... If you do it in gear, the inertia of the car moving is able to keep the engine running without using any gas the only thing is, my honda is a manual, my question is - is it the same in my QX4 automatic?

[ubpsanity]

oh, good call there fueler...

You're absolutely right about the difference between manual and automatic. My Spyder is a manual, and leaving it in gear is better than dropping it into neutral..

But with the Pathfinder, due to it being an automatic, it needs to keep the engine running with no load on it. but it's fairly close, so depending on where I'm stopping I'll shift to neutral so I can coast farther. but if close, I'll leave it in gear to get the bit of engine braking I have..

[fueler]

But with the Pathfinder, due to it being an automatic, it needs to keep the engine running with no load on it. but it's fairly close, so depending on where I'm stopping I'll shift to neutral so I can coast farther. but if close, I'll leave it in gear to get the bit of engine braking I have..

Hmm i did not take into consideration the extra distance i get in neutral. Also, is it OK to switch from N to D and vice versa while moving? (somewhat slowly of course) Ive been doing that with my QX4 for 70k miles with no problems, but my chevy truck does not like that at all (makes a nasty noise) The most important factor, in my opinion, is freeway speed. I get pretty good mileage at 65 mph and horrible gas mileage at 85+

With gas prices the way they are, I plan my day out differently, to be as efficient as possible. I do not drive any farther than I need to. But I still love my 4x4 and decided against selling for the moment.

[ubpsanity]

Also, is it OK to switch from N to D and vice versa while moving? (somewhat slowly of course) Ive been doing that with my QX4 for 70k miles with no problems, but my chevy truck does not like that at all (makes a nasty noise)

Ya, should be ok to switch as much as you want, as long as you don't shift into 1 as you're doing it. Or R for that matter.

I find I can't just drive slow to save fuel.. I want to be in the top 15% of the cars moving. if cars are passing me, I'm not going fast enough. Although I've tried it, and going slow does save fuel. Going faster saves time, whats more important to me?

[SnowSurfLax]

Ya, should be ok to switch as much as you want, as long as you don't shift into 1 as you're doing it. Or R for that matter.

I find I can't just drive slow to save fuel.. I want to be in the top 15% of the cars moving. if cars are passing me, I'm not going fast enough. Although I've tried it, and going slow does save fuel. Going faster saves time, whats more important to me?

Yeah, I'm with you. I can't stand it to have lots of people passing me most of the time.

On a long drive, I can handle just setting the cruise at 70 except for the fact of all the idiots around me who can't hold a steady speed. 80% of the time driving on the freeway I can't use cruise control because I have to constantly manuever around or slow down if I can't. Totally negates the purpose of cruise control.

[Infinitidood412]

was it easy to remove the roof rack? i hate how that looks

[KoukiS14]

Yeah, I'm with you. I can't stand it to have lots of people passing me most of the time.

On a long drive, I can handle just setting the cruise at 70 except for the fact of all the idiots around me who can't hold a steady speed. 80% of the time driving on the freeway I can't use cruise control because I have to constantly manuever around or slow down if I can't. Totally negates the purpose of cruise control.

christ almighty. . . that's by far, my biggest peeve. That really angers me when people can't figure out their cruise.

[Buzzman]

christ almighty. . . that's by far, my biggest peeve. That really angers me when people can't figure out their cruise.

Slightly off topic (pet peeves I mean), but I'm 100% with you on this one.What pi$$es me off the most is when I'm comfortably running on cruise, and some idiot passes me, then pulls in front, AND SLOWS DOWN. This forces me to either cancel my cruise, or pull out to pass him, at which point, of course, he SPEEDS UP again. AAARRGGGH.That, and left lane parkers. My 2 biggest pet peeves.As far as saving gas, every time I fill up my Pathy, I vow to change my driving habits, to slow down, and to save gas. I'm lucky if I get past a quarter tank before I'm back to my old habits. Tough to change after 40 years.As far as tire pressure goes, I run at 34PSI, and I check at least once a month.

[SnowSurfLax]

was it easy to remove the roof rack? i hate how that looks

Not hard at all. Just need star bits for the screws on the back end of the rails. Just loosen all the nuts on the rack assemblies and slide. Took me 20 mins. My butt dyno can feel the lessened resistance.

Slightly off topic (pet peeves I mean), but I'm 100% with you on this one.What pi$$es me off the most is when I'm comfortably running on cruise, and some idiot passes me, then pulls in front, AND SLOWS DOWN. This forces me to either cancel my cruise, or pull out to pass him, at which point, of course, he SPEEDS UP again. AAARRGGGH.That, and left lane parkers. My 2 biggest pet peeves.

Yes and yes! My wife upbraids me when people do that and I let my road rage instigate my temper. Of course, she does the same thing with left lane parkers. I've seen her flip someone off for not moving!

[carnal_c30]

damn only way I'd get that in my Qx4 is rolling down a big long hill.... I've done all the maintanence and then some, but bigger tires, brushguards and all that slow me down

my best is 18mpg

[Infinitidood412]

this is a hard question to answer, but does the Q look decent without the rack? i have taken the air deflector off the back and i have those pillars pointing up and they look kinda weird by them selfs. mind throwing up a pic or two?

[LeroyBrown]

i have a 94 nissan pickup 3.0 v6 and i save tons of gas i get 20mpg in the city by just shifting at 2000 rpms. ill be going 30 in 5 gear just cruising saving the gas lol just as long as the motor doesnt start bogging im a ok

[kamiar]

this is a hard question to answer, but does the Q look decent without the rack? i have taken the air deflector off the back and i have those pillars pointing up and they look kinda weird by them selfs. mind throwing up a pic or two?

off topic, i would buy the spoiler if you don't plan to use it again...

[SnowSurfLax]

this is a hard question to answer, but does the Q look decent without the rack? i have taken the air deflector off the back and i have those pillars pointing up and they look kinda weird by them selfs. mind throwing up a pic or two?

From a distance it looks good, very slick. I don't have the spoiler on either and it only looks like a couple of horns on the back end at close up. But mines black too, so it blends in...

[ifyaknowatimean]

Just something mentioned further up above.Air intake systems and exhuast systems do increase efficiency. At first this may seem a little weird, because they jack up power, but trust me, I'm an aerospace and mechanical engineer. This is what my life's work is devoted to.How much fuel you burn depends on 2 things- how fast your engine is spinning, and how much fuel your injectors are forcing into it.Though an air intake necessitates a little more fuel, the extra power means the engine can run at a lower RPM rate and still maintain the same speed. Additionally, if you're somewhat aggressive in nature, the extra power keeps your foot off the gas more (hopefully), thereby saving fuel.Biggest thing, change your driving style.in case you didn't know, air resistance is a function of 2 things- the square of your speed, and the coefficient of drag.For the speed- 80 squared equals 6400, 65 squared equals 4225. Therefore, your car has 50% more air resistance at 80 than at 65- that's a real ugly number. Air resistance turns from a significant factor in efficiency to the primary factor.As for the drag coefficient, there is very little you can do that will have any significant impact short of putting ugly covers over your wheels, ripping off your mirrors and rack, and redoing the body of your pathfinder to a streamline that will have a big effect.The biggest thing that will save mpg is driving conservatively.

[bmlawless]

I got my best mileage last weekend since buying my QX4 last December. I got 18.4mpg with a combination of 100+ miles of dirt roads at right around 30mph and another 50 miles of paved at around 70mph.

Here a pic with my rack photoshopped off:

As for the drag coefficient, there is very little you can do that will have any significant impact short of putting ugly covers over your wheels, ripping off your mirrors and rack, and redoing the body of your pathfinder to a streamline that will have a big effect.

I took your advice:

[Infinitidood412]

This is how my Qx4 currently looks. Kinda weird with that thing off the back...The luggage rack is off