I got an 03 6 speed about 2 weeks ago with 21 mpg on the display, and it has gone down ever since. Tonight I got gas, and calculated it to be just over 15 mpg. I mean, I'm not the best at shifting yet, but I wouldn't think that it would have THAT great of an effect on it. On the display right now, it says 18.5 mpg... however, as I said before, I calculated it to be just over 15 when I filled up tonight. Why the huge discrepancy between those numbers? Am I calculating it wrong? My process: I reset my trip odometer everytime after I fill up. Then then next time I fill up, I take the number of miles I've driven, and divide it by the number of gallons it took to fill up the tank (Tonight I drove 204 miles and it took about 13.4 gallons to fill up). That's the right process to calculate it right? Why is my calculation so vastly different than the display on the car?

I do city driving, and I don't redline the car. For the most part, I take it easy, but I do occasionally take it up to about 4-5k to shift. Like I said, i'm just learning to drive a stick and my upshifts are kinda jerky, but gotdamn. Would it make that huge of a difference in MPG?

These numbers are very disappointing, because one of the reasons I justified the increase in cost of getting the new car would be the saving in gas mileage. But now, it's basically the same as my old 2001 auto. I'm quite upset. What the hell is going on?

 

Winter Blend gas is probably not helping either. Also, gas with ethanol tends to drop gas mileage.

 

OMG... not another gas Mileage thread

 

since the temp is changing, check your tire pressure because it can decrease it a good amount which would significantly change ur mpg

 

I get the same, my computer usually tells me I'm 3 or 4 mpg higher than what it really is... My sparkplugs are shot (94K) and my Airfilter is dirty. I am putting those spacers from aaron on...So, I'll see what happens now.

 

Put more air in your tires, about 5psi more than what Nissan recommends. Also, try skipping gears. Go from 1st-->3rd-->5th or 2nd-->4th-->6th. Keep the revs below 2K rpms when shifting. Always use 6th gear when cruising on the street or freeway.

 

i always try to keep it in the highest gear possible when cruising.. i might try that skipping thing

 

thats weird.. why the hell is that? my sparkplugs should be good.. im only at 49k.. so you get the same gas mileage as i do? is something wrong with our cars?

 

Mileage will vary from car to car, how well its maintained, and driving style all effect it. As stated before, bumping tire pressure helps. I run my fronts at 40 psi and my rears at 38 psi. The EPA suggests getting up to cruising speed "quickly", then skip to the highest gear. I drive almost 40 miles each way to work and back...half highway, half city. My average mileage using premium fuel is around 25-27 mpg, and regular fuel usually runs around 21-23 mpg. I didn't think fuel grade would make a difference but I tested them both for 4 full tanks using actual mileage.

 

if you dont want to spend money on gas...get another car

 

Mine usually always stays around 26-28 mpg but I drive mostly all highway miles,and mine is auto at 42,000 miles.Def check tire pressure after each fillup and keep learning that manual stuff..lol...Could just be a combination of things as well as city driving.

 

Are you driving far enough for the car to fully warm up? How bad is the traffic where you live? Spend a lot of time idling at lights?

Traffic lights blow goats here. Cross street traffic lights change for no reason, 10 PM at night and the lights still operate on a morning rush hour cycle. I swear, traffic engineers are the stupidist people on the planet. Just kills my gas mileage and my average speed this last fill-up was 32 mph...and about 20% of my driving was on the freeway and the rest on streets with speed limits of 35 mph or higher. I've been averaging around 19.5 mpg since I got my car in mostly city driving...in fact, this last tank was 19.5 on the dot (okay, 19.48!) but my trip computer showed 22.8. It generally is 3-4 mpg off in city driving. Maybe idling so much throws it off.

 

so you got a 03 max to save gas mileage compared to a 01? hmmm 3.0 to 3.5. check your numbers again buddy.

 

I'm not going to worry yet, non hwy mileage is always crap around here till April. I typiclly lost 3-5 mpg in the winter. Having the extra power of the 3.5 eases my pain too. I'll send you a pm if my numbers improve with the work I did this weekend...


spacers almost complete...

 

Very nice!

 

yeah.. i always make sure my car is fully warmed up... i'm gonna try it on my daily commute and see how bad it is... the traffic isnt horrendus, but it's just the lights that make the difference i think.. but even those arent too bad.. less than a minute for red lights for the most part... like i' said, i'll see what happens on my daily commute and see how it compares to my old car

 

or a freakin bicycle.. but i was expecting an improvement.. not for my gas spending to completely disappear

i thought there was something wrong with my car since i countinuously got 15-16 mpg no matter how slow i drove or what kind of roads i drove on.. plus manuals are better on gas than autos

 

wow... reading this thread makes me feel good that with close to 160K on an 01 auto I still get between 19-22 in city and 27-29 on hwy.

Wanna trade cars?

 

It's a well known fact that the trip computers on the 5.5 gens are not accurate. They read between 2-4 mpg's higher than reality. Your own calculations are the most accurate.

And although you shouldn't expect 30 mpg, the 15 mpg's that you are getting does seem low. With only 49K on the car your spark plugs should be fine but there could be another problem. I'm getting about 20 mpg's on my 2002 auto in the winter.

 

i'm so jealous.. lol

 

What you mean? Do you start moving when the car is fully warmed?!

 

I stopped caring about my Gas Mileage a long time ago..

Once I put the 6th gen tranny in my car, I knew I would lose my miles...

but... I will say I am a spirited driver, I shift between 3,500 RPM and 4,500 RPM as a daily... I get about 20 MPG (Display)... though my best was highway with my old trans, i got 36 MPG (Display)

 

When I was a first-time shifter, I never got mileage as bad as yours, I was getting about 20-21. Just by learning better shifting habbits and becoming more experienced I now get 22-24 (city). So time will help a bit.

 

that was by your calculation or what the number said on the display?

 

My Calculation.


The week after I brought my car home, my display was around 23-24. Now it's at 32.

But by calculation I'm generally around 23 for city. It waivers depending on how spirited or nonspirited I'm feeling during the tank.

 

the vq power makes up for the damn horrible mpg

 

Since we're on the topic of gas mileage:

Would higher elevations lower or increase gas mileage?

I would think it would matter and should be considered when talking about MPG.
Please correct if I'm wrong.

 

One thing I was wondering about is, if with the factory tune, our cars run rich, would adjusting the AFR with a SAFC2 help raise the gas mileage? I'm sure my car runs rich because every time I start it in the garage, it fumes it up bigtime. I drive 50city/50highway miles and I get right around 20-22 mpg.

 

Altitude doesn't affect my mileage. AFC doesn't show any noticeable improvement since part throttle AFR is not and should not be altered. Never believe the trip computer, this has been established long ago. If you want to save MPG's, make sure the car is running tip top, get lightweight wheels, a different FD/6th gear and change your driving habits..

. . . . .

 

Do it! The VQ35 makes enough torque down low so even if you skip gears you will easily keep up with traffic. Don't try this with a Honda engine, they have less torque.

 

I get anywhere from 22 to 26 mpg, depending on driving conditions. And, yes, the car's computer is consistantly 4 mpg higher than the actual figure. Mid-teens is horrible.

 

Similar issue here Bought a 2003 Maxima SE Auto with 48,000 miles on in a couple months ago in good condition from a reputable dealership. The dealership some basic maintenance on it before selling the car to us including an oil change, and engine air filter, and alignment.

Now after driving the car for a few months we've noticed some pretty poor gas mileage ratings. From the last two fill ups we're avg between 12-14 mpg! (calculated from the amount of miles driven from the trip computer vs the actual gallons used to fill up the tank) This is well below the Maxima's revised lower city rating of 17 mpg. I really don't have any explanation as to why it's so low and I'm concerned there might be something wrong with the engine. Although there isn't any obvious signs as to what might be causing this mileage drop.

I will note that:
- Our mileage has been almost all city driving vs hwy (90% city, 10% hwy)
- Have always used premium grade branded gas during fill ups
- Tire pressure was checked, no check engine lights or anything obvious is wrong with the car,
- Engine and transmission running smooth, no rough idle
- Outside temps have been in 40-50's outside when driving, but nothing super cold temps
- Car has been driving lightly, I don't floor it or drive aggressively.
- The carputer says that we're averaging 17.3 mpg which is way off from what our actual mileage has been

It's really interesting how varied people's mileage ratings are here and why ours is just plain lousy

 

i did! i tried it last night for the first time and it worked nice.. i skip from 1st to 3rd, and 3rd to 6th.. i make sure to keep my rpms low to use as little gas as possible.. but i can't resist a 4-5k shift every now and then but that's not that often though.. i'm testing this tank of gas to see what my mileage is like using mostly low rpm shifts... and if it's STILL bad, i'm gonna switch gas stations.. because i should not be getting 15mpg... i heard certain stations can do weird stuff with their gas to throw off gas mileage.. and that actually would explain why my mpg has gone down over the 3-4 times i've filled up ever since i got the car.. hmm....

 

if you are skipping shifts to save gas...you shouldnt have bought a 6 speed VQ35

 

even with that much city driving it should be nowhere NEAR 12mpg.. V8s dont even get mileage like that.. try switching gas stations.. thats what im gonna do.. maybe it'll make a difference

 

this is merely a test to see if i'm still getting horrible gas mileage even with the most least aggressive shifting.. i dont plan on doing it as a daily practice

 

oh yeah, i forgot to mention i do use 87 octane gas

 

SIKE!! just joking.. dont flame me.. lol.. of course i use 93

 

Yeah we've had a couple of fillup's at Chevron, and we just tried Shell now (all premium gas). The 12mpg we got was very SUV like which is nuts.

I'm wondering if I took it into an auto shop if they could even determine what the issue might be

 

No kidding. I was getting 21 mpg average with the same type of driving with my 626 that yields 19.5 in my Maxima. But I will take that slight hit for the extra 85 hp I get with my Maxima.