I would like to keep this a serious thread. If you have nothing positive (criticism is perfectly acceptable) to say please do not clutter the thread. I only ask that you give reasons for your idea(s).

I am brain-storming ideas to increase MPG. I did quite a bit of searching; almost all of it was regarding basic PMCS and small changes to driving habits.

A couple of months ago I read a really cool write up in some magazine my friend bought. He took a Integra that was old and tired apart. After doing a bunch of work he was able to go from 20MPG to almost 40MPG (http://www.importtuner.com/tech/impp...yle/index.html). Pretty impressive IMO.

At any rate I am having trouble figuring ways/areas to copy his ideas. Really I can not do all that much and still keep the maxi passenger friendly.
Here is what I have thus far:
weight reduction [very few opportunities]
home fab'd body parts
undercarriage panneling
new engine with some article-like part upgrades (possibly the QR, MR, KA, or SR).

I would like to keep the Maxima as passenger friendly as possible. Also please weigh, and include where possible, the gain vs cost. It looks as though he dumped in about 4k+... not realistic for most.

 

I guess this would fall in the lines of weight reduction, but u cd always try lighter rims/wheels.

 

-aftermarket y-pipe or just high flow exhaust in general
-light weight/underdrive pulley
-cold air intake
-coilovers(lighter then stock suspen.)
-lighter rims /\
-racing seats
-take out a/c, lines and condenser
-take out spare tire(if your not worried about a blow out)
-try not to burn out all the time

 

what is the weight usually for the stock 15s on the maxima/i30? 95-99. i was wondering about that too maybe the stock are heavier than aftermarket rims??

 

Light rims and low profile tires at 40 PSI. What is the majority of your driving? City, highway, or mixed. If city, drop to a slight ly shorter tire to decrease load on the engine with stop and go traffic. If highway, go with a taller tire increase MPG.
Less weight in the trunk, lose the 15s in the band-pass and get 8s in the deck with a small amp.

 

For starters, what is your MPG currently?

 

my mpg average is 25 city driving (99 auto)

my mods are simple i/y/cat back most importantly NO SES LIGHT they kill mpgs

if the mods i have are done i would recommend maybe heavier duty gaskets and seals and go with 0-20 oil

i dont know exactly how much time you plan on investing in your ride but this may help
i also have no clue where you would find something like this its as of right now only a "brainstorm"

oh and try to keep your foot as light as possible

 

This is going to nut and off the wall, but put a turbo on it. A well tuned low psi (6 to 8 pounds) turbo set up can give you outstanding mpg if you can drive with restraint if not using all the new found power. They are very good at increasing low end torque (when sized right) witch means you have to hit the gas less to do the same job as be for. This would take a good turbo guru that understands how to set one up for economics and not power. O turbo has no added drag on the engine unlike a sc.
I use to have a 10sec DSM that if I did 65 on the high-way I could pull off 35mpg. Could not give you an around town number as I think I was always on it light to light

 

Isnt the rule of thumb to keep out of the boost below 3K?

 

It seems like to raise MPG you might need to go into modding and driving conservatively.

My car is completely stock, and I've done everything under the car rainbow and it still stays at the stock MPG figures. Either I've approached the maximum efficiency for my car with stock parts or my odometer is playing mind games with me.

1. I've changed all spark plugs to the NGK platinum.
2. K&N air filter
3. Cleaned TB, IACV, and all that
4. Tried 0W-20, 0W-30, 5W-30, 5W-40, 10W-30 all full synthetic, with no change.
5. New coolant (Full flush)
6. Changed all 6 coils on the coil packs (Ran smoother with less engine vibrations but no MPG change)
7. New knock sensor
8. New knock sensor harness
9. Drove super conservatively never let car go above 2K RPM and stayed at 55-60 on freeway (No change)
10. Drove crazier with max RPM going only to about 3K and highest speed on freeway at about 65-70 (No change)
11. Drove even crazier (MPG dropped down by 5)

Heck I even change my power steering fluid and took everything out of the trunk (spare tire, tools, skeletons) the car won't give me those precious numbers.

As of now I am getting about 18 MPG city and 23 MPG highway.

 

YEEEOWWCH
is your maf dirty? that seems low

 

With all thing the same, are engine seem to have peak torque around 3000rpm (seat of the pants guess) What you would want is a set up that would be putting about 4 psi at 3000rpm and at red line about 8psi. For mpg you want a small fast to spin up turbo so you can start to feel boast by 1100 to 1300 rpms. This way when you are at cruse or around town just a light foot will get you moving to where you need to be. Also turbos are much more efficient with an at trans then with a manual, no loss of boast in between shifts

 

I replaced my MAF about 5 months ago

But even before my OEM MAF died I still had the same numbers. How is this possible!!!

I think I'm just gonna get super big wheels and tires and trick myself into thinking I'm getting better MPG.

 

3.5 full swap w/auto tranny. The 3.5 has power to spare, which increases MPGs in a lighter, older Maxima. And the 4AT is geared tall enough to get decent highway MPG's.

lighter wheels, narrow tires (less rolling resistance)

base model Maxima's weigh the least, so if you have power seats, lose 'em.

When I had my stock 16" SE wheels, and my car is a base SE no sunroof or power seats (it has power seats now and 18" heavy wheels) I could regularly get low 30 mpg's. That's with 255HP available if I need it.

Now that I have HEAVY stock SE 18" wheels with wider tires, I can only get about 27 MPG on average. I lost about 4 mpg's just with my wheel/tire setup

 

Minus mods, weight reduction, etc. I think the single most effective way to increase your MPG is to be easy on the gas. I notice several MPG difference if I dramatically change my driving habits and stop quick takeoffs, driving at 80+ on back roads, etc. If I'm looking for good MPG, I don't take the 4-mile road with 12-18% grades home, either...having my foot halfway to the floor that long can't be good for the mileage. Sure, it's quicker, but I can also go 10 miles around and have a more gradual climb.

...but, who am I kidding...they're Maximas, and most Maxima owners (myself included) aren't exactly light on the gas.

 

Have you tried replacing all the gaskets from the LIM on up? Id also try coppers plugs as well. Ive had some good experinces with just swapping out plugs to just copper.

 

plugged fuel filter maybe?
dirty injectors?

i think something has to be wrong

 

It seems like its all been said. I can tell you NOT to buy one of those little fans that goes into the intake pipe or one of those cheap "performance chips".

 

I've done a bunch of work on my Max (5-spd) recently that has 212K miles. Mods include WS Y-pipe, Stillen short-ram, and Flowmaster 60 series muffler. Recently replaced fuel filter, knock sensor and cleaned throttle body. Right now, front struts are swapped with Tokico Illumina's with a fresh alignment (rears being replaced this weekend). Last time I went between home and school (225 miles) with heavy head and cross winds, I got 30MPG going 79-80 MPH. Maintenance, upkeep, and simple exhaust/intake mods is what has helped me the most.

 

i get 15-19 mpg on my 97 GLE, i have the stock rims from a 2003 maxima on my car, which are 17 inch, and much heavier than my old wheels, could this be a reason for my bad gas mileage? or would a change in wheels not affect the mpg that much?

 

At least one of your upstream O2 sensors are going bad. Mine did that years ago, I went from 30mpg to mid teens in one day, the O2 sensor was lazy, but not bad enough to throw a CEL. I could see on a OBDII scanner that one of my O2's was just kinda stuck on a lean reading while the other O2 sensor was swinging around stoich normally. SInce the ECU thought the engine was running lean, it dumps more fuel in.

 

I plan on doing the underbody paneling. I am going to buy sheets of ABS plastic and cut it out to w/e shape I need. I plan on have access panels for coolant draining, oil change, and a few other things.

 

Hello, I know this thread is a little dated, but I've been kicking around the underbody panels idea as well. Did you every do that? If so, I would be interested to hear how it went and any mileage increase numbers.