jphoto

First, the car. 2002 SE, automatic. Myself, the wife, three-year-old, some luggage but the car wasn't stuffed or anything.

Today I was on a three-hour highway drive, and according to the on board computer, I was getting 11.1 L per 100km's fuel economy. For the American folks, that's 21.2 MPG.

Average speed during the trip (cruise control) was mostly right about 110 kph (68.5 mph).

Am I being suckered in by the EPA's famously optimistic ratings, or is something wrong here?

footballplyrdan

the epa rates the 5 gen max with 19mpg city and 26mpg highway. With the extra weight and your higher speed, it seems to be about right. Plus, the mileage will vary with the weather, conditions, and the age of the car.

VaporHead

I agree. I get around 20-24 mpg highway. Sometimes more, sometimes less, depending how heavy my foot is that day and the load.

getbigtony

iTrader: (1)

i don't know, if it was mostly highway, i'd say its wrong.
even when i go to work only, with a mix of 30% city 70% highway, i get 21mpg. and on the highway, i'm goin around 75mph.
but of course i have a 3.0 5spd, so i can't really compare

Maxi113

iTrader: (3)

Wow with all the crap I have on my car, my mileage is no where near that! =0 oh well..

jphoto

So the general opinion seems to be, not great but not far off. Bah. I was almost hoping there was something wrong so I'd have an improvement to look forward to after some sort of correction.

Maybe I'll do a comparison test after I starve myself down to 97 lbs, leave the wife and boy at home, and rip out all the bits of the car that aren't needed (spare tire, rear seats, radio *****, sand the paint off...).

opanick

iTrader: (1)

well i know since i put my berk intake my mpg has gone down from 21.6(stock) to 20.3(berk intake), so im wondering if I did something wrong with the intake or if im just punching it too much to hear the sweet sound it gives off LOL

Atl92Se

iTrader: (9)

I have the same problem with my Max but I stopped complaining when I drove my wife's SUV.

SEmy2K2go

iTrader: (10)

You cannot go by the car's fuel economy computer. You need to calculate the mileage yourself at your next fill-up.

lowincash

iTrader: (2)

yup my display says i'm getting 22.1mpg but when i calculated i was getting 16.7mpg...as a matter of fact my display have been saying 22.1mpg for a long time now lol

N1sMO

^^
You can hold down the Trip button on your steering wheel until the it displays dashes and it will reset the MPG counter.

I just drove back from Frankfurt yesterday with 4 adults and luggage and the car averaged 27 mpg (mostly due to me chasing a BMW 335i coupe test mule). Ofcourse, it is more accurate to calculate the mpg yourself on the next fillup but in my experience the computer is pretty accurate. I reset the MPG everytime I fill up.

p.s. the 335i has some serious power, as it didn't just walk away from me once the Autobahn opened up, it freakin' flew away. But I was a lot heavier than him though.

† ErV †

i've gotten under 20.. my best sustained was like 25, giving me ~420 miles of travel.

of course that includes a nice 100mph cruise for about 50 miles (i love bikers!).

but i don't reccal ever hitting over 25, for the 3 years i've had it

steven88

iTrader: (28)

that seems kind of low...especially if you are cruising on the highway...but our on board calculators are very inaccurate...so go by the actual calculations at the pump next time...

my best mpg was 25.5 with all highway cruising at 75mph...i thought this was kind of low...but hey, every car is a little different...my city mileage blows at 16-17mpg...

driving styles vary as well...

jphoto

I'll do a calculation in the near future and compare it to the computer. Should be interesting.

You'd think they'd have no problem making those things accurate...

Puppetmaster

iTrader: (48)

Another vote for doing the calculation yourself. Check your tire pressure as well.

Btw, at ~110 kmh/68 mph on the 4ATs, what is the RPM reading?

jphoto

I recall sitting right on 2500 rpm most of the time.

MacGarnicle

iTrader: (1)

110 isn't too bad.. optimal fuel efficiency is around 100km/h (60mph). If you're going 75mph, you're reving the car pretty high and are probably not going to get very good mileage "even though it's highway mileage.."

Just make sure your tires are properly inflated.. and of course there's tune up stuff you can do to maximize your gas mileage.. overall though, don't expect the Max to be able to reach 30mpg...

BigFly_2K2SE

iTrader: (1)

I am going to buck the trend here and say something's wrong.

I realize that the trip computers are highly inaccurate. However, at least in my 2K2, the trip computer is consistently inaccurate. I can pretty much count on it to be about 5 MPG optimistic on every tank. So while you cannot rely on it to give you the correct reading, for me it is still a good gauge on how I am doing.

I often make highway trips with wife, 3-year old, and luggage, and at 110km/h, my trip computer would be reading somewhere between 7 & 8 L/100km. This will consistently convert to an actual consumption of between 8.5-9.5 L/100km.

Travelling at about 140km/h, going mostly uphill, and ploughing into a headwind, the WORST my trip computer will read on the highway is about 9.5L/100km.

I am a 6-speed and you are an auto so there might be a little difference there, but 11.1L/100km is ridiculously high for highway driving.

In any case, I would agree with those that say calculate by hand and see what you get. If you are not getting around 10L/100km or better travelling at 110 kph on the highway, something's wrong.

frankd121

iTrader: (1)

last road trip i went on i averaged 75 mph and was getting 28 mpg. (1 mpg better than epa)

charr82

iTrader: (3)

I consistantly get 26-27mpg in mixed driving (70% hwy/30% city) every tank. That's my calculated mpg. The computer always reads about 29-30mpg so I just ignore it. I have an '03 with about 170,000 miles. I think it all has to do with your driving style. I typically drive 5mph over the posted limit except in town and my car sees 80mph pretty regularly when I'm passing cars. I rarely top 3500rpm when I accelerate and I coast as much as I can when I go to stop. I can't really complain about the mileage. I think it's quite good for a v6 with 255hp.

trigger005

iTrader: (8)

theres a thread on fuel economy every week

die thread

die

Atl92Se

iTrader: (9)

there's people in here got up to 30mpg. Forgot who but yeah.

MacGarnicle

iTrader: (1)

I'd like to know how... with weight reductions? swap for a smaller engine?

00Max00

Too many indefinite factors that affect fuel economy. The biggest one I believe is the alcohol content in the gas you are using. Since the government's pushing hard on alternative fuel like ethanol which contains substantially less energy than pure gasoline, will surely causing much worse MPG than you would get years ago.

00Max00

Too many indefinite factors that affect fuel economy. The biggest one I believe is the alcohol content in the gas you are using. Since the government's pushing hard on alternative fuel like ethanol which contains substantially less energy than pure gasoline, will surely causing much worse MPG than you would get years ago.

Dust N Bones

iTrader: (1)

I'd say there is definitely something wrong. Like others have said the on board trip computers are very inaccurate, they read about 3-6 mpg's higher than reality. So in reality you actually got about 16-19 mpg. If your average speed was 68 mph there most likely is something wrong.

Nvious

Bingo. Since the only way the computer is reading fuel use is by fuel pulse duration (which is a somewhat of an inaccurate reading since although fuel pressure is somewhat stable, its not always a dead on constant psi)

Plus you gotta figure in normal fuel vapor loss through the evap system which of course bypasses the normal fuel delivery system.

Maxi113

iTrader: (3)

ok so I figured out mine. I get about 18 city, and well highway it varies. If I go about 140-160 I get really crappy mileage (gee I wonder why :P ) Going the normal 69mph I get about 22 or so. I don't drive highway often so that's a crappy guess :P

Puppetmaster

iTrader: (48)

For more gas mileage comparisons:

http://forums.maxima.org/showthread.php?t=392493