Posted: Dec 18 2007 at 12:47pm | IP Logged

I also have the same problem, 07 Frontier crew cab, 4x4, v6.  I bought the truck new in July and averaged a steady 20+ mpg, city/hwy commute (about 20 miles), easy driving, well documented.  Right now (PA winter) I barely get 14-15 mpg, same commute  and driving habits.  Truck is garage kept and no 4x4 has been used yet.  Dealer checked it out and said there isn't anything wrong with the truck.  But I'm losing 25%-30% in fuel efficiency - That's an extra 1/4 tank of gas burned per fill up!  Yes, I've checked tire psi, used 87-94 octane, etc., and everything else mentioned in these posts - nothing helps.  I haven't changed the air filter yet (it's not dirty at all), but I only have 6k miles.

I even had my cousin check his 07 Pathfinder v6 against my truck for a month, filling up at the same station, same octane, similar commute.  He's still in the 20+ range.

I'm hoping someone out there has seen the same problem and has an answer other than "driving habits."  This truck is burning more gas than the hemi I traded in!!!

Posted: Dec 18 2007 at 2:28pm | IP Logged

Same thing happened to me recently.  I was around 20 mpg (average of MANY tanks) and suddenly dropped to around 18 (same routes all the time for 3 tanks now).  It coincided with my switch to 93 octane.  Next tank I'm switching back to see if that's it.  Truck has 25k miles SE crew 2WD.

Posted: Dec 18 2007 at 3:42pm | IP Logged

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Keep in mind guys the vaporization rate on winter gasoline changes and that means better starting but worse fuel mileage. Buy your gas early in the morning but don't over fill it.

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Ho, Ho, Ho, (as in laughing )Make Mary and Jump for Joy… Halleluiah brothers… Amen

Posted: Dec 18 2007 at 5:59pm | IP Logged

just to keep you up to speed.....so to speak.

on monday i went to the nissan dealer and got an oil change. didnt go synthetic .......cant justify the additional $$$

we put in a new air filter; he said it looked like the original one; he gave me all the advice received above including the comment that mileage is always worse in the winter.....

i left the dealership on empty, filled it with 91 octane and drove yesterday and today a total of 260 miles, mostly on the highway, mostly with the cruise set at 70mph, and i am empty according to the fuel gauge. havent filled it but i expect it will need 65 litres tomorrow morning. that is 17.2 gallons and about 15.2 mpg.

that is just bulls**t from a 6 cylinder motor. and winter has nothing to do with it because that is the mileage i have been getting since i got the truck in september. I have a 505 hp vette that can give me 26+ mpg anytime i keep my foot out of it.

my rpm at 70 is 2000 on a level surface; is that about correct??

Posted: Dec 18 2007 at 11:46pm | IP Logged

66L72 wrote: that is just bulls**t from a 6 cylinder motor. and winter has nothing to do with it because that is the mileage i have been getting since i got the truck in september. I have a 505 hp vette that can give me 26+ mpg anytime i keep my foot out of it.

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66L72:

... Ahhhh... You have stumbled on the answer... Just make your TRUCK as aerodynamically clean as a vette!... Our new Camry 4 banger only got 24 mpg... and that is gentle driving. But it only has 450 miles on it and filled with gas once by us.

I switched two of my Nissans to full synthetics in the engine and didn’t notice any improvements in MPG.

... On vehicles with carburetors I’ve always been able to achieve the best fuel mileage that could be expected from that type of vehicle. But the modern injected vehicles require many sensors and a computer program that guesses how much gas to inject from the input of the sensors.

... It doesn’t take much of a combination of sensor errors to reduce fuel mileage. Then you throw in problems with catalytic converters, EGR valves, carbon build-up, and lousy gasoline it’s a wonder they perform as well as they do.

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Ho, Ho, Ho, (as in laughing ) Make Mary and Jump for Joy… Halleluiah brothers… Amen

Posted: Dec 19 2007 at 8:50am | IP Logged

66L72 wrote: i left the dealership on empty, filled it with 91 octane and drove yesterday and today a total of 260 miles, mostly on the highway, mostly with the cruise set at 70mph, and i am empty according to the fuel gauge. havent filled it but i expect it will need 65 litres tomorrow morning. that is 17.2 gallons and about 15.2 mpg.

Um... you can't measure it by how much you think it'll need.  You have to divide the actual amount burned by the miles traveled.  Comparing a vette to a pickup is literally apples to oranges -- THERE IS NO COMPARISION. 

66L72 wrote: on monday i went to the nissan dealer and got an oil change. didnt go synthetic .......cant justify the additional $$$

Change your own oil.  It costs me about 25-30$ to change my own with fully synthetic.  There is no excuse for this, changing your oil is easy and basically anyone can do it.

66L72 wrote: from a 6 cylinder

Gas mileage has very very little to do with how many cylinders a motor has.  Thing more important than the number of cylinders include: tire outside diameter, aerodynamics, gearing, efficiency, weight, etc. etc.

Posted: Dec 19 2007 at 9:37am | IP Logged

hi again

i know the vette is a tad more aerodynamic than the nissan and its not a valid comparison........just me venting

for sure i know how to change the oil; i am a motorhead like you; i did a complete body off restoration on a 66 vette...... i have had skinned knuckles etc.

fact is crawling under the truck in the snow and minus 10 degrees doesnt really appeal to me; and the oil alone is $50 up here.

and yes i know that an estimate of what it will take to fill the tank isnt accurate; i will fill this morning and put another 100 miles on at least today and see where it ends up. but the milage calculator on the dashboard says 15.2 again and i have no reaso to doubt it.

re the tires ...... yes i replaced with same size good years and i keep them at 38 pounds.....

what frustrates me is i really like the truck. it is tight, no rattles, handles well etc etc......... just an absolute pig on gas!!!!

Posted: Dec 19 2007 at 1:45pm | IP Logged

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66L72;

... A big question here is why was the truck traded off?

What modifications or PO flaws have been covered up by the PO or the dealer? Who knows… Maybe the timing chain is a tooth off from the assembly plant. It could have been flooded, overheated, driven abusively, or as one member over oiled an air cleaner element and screwed up the MAPS. Really I’d think it should get 20MPG sustained smooth highway and 17MPG city driving in the Summer time and one or two MPG less in the winter.

... When my ’99 fuel mileage fell off I poured a bottle of Lucus fuel treatment in the tank and the MPG increased nearly two MPG after a couple of hundred miles…

BTW... I still have my '99 'cause it has zero problems and I love it. When it has problems I'll no longer love it and will shuffle it off onto some other poor soul.

To quote Red Foxx " I'll love you when you are old, tired, ugly and broke... but I won't be with you..."

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Ho, Ho, Ho, (as in laughing ) Make Mary and Jump for Joy… Halleluiah brothers… Amen