# Is 18-22 city MPG (with A/C) normal?



## TheBrownRobert (Aug 28, 2007)

Hello. I'm new here...

I have a 1993 Sentra E, 1.6L, Automatic, 123000 Miles. I'm not sure whether my car is getting the gas mileage it should be getting, and I want to know if maybe some other Sentra owners could enlighten me with their mileage or give any tips to improving efficiency. Maybe my car's normal, maybe there's something terribly wrong. I dunno, I could use some advice.

All of my driving is done in the city. Without the A/C, I get about 24 MPG. With the A/C, I obtain an absolute maximum of 22 MPG under normal/light driving, with it sinking as low as 18 MPG under normal/hard driving.

My car is slooow... I have trouble keeping up with a bus. If I give it a lot of gas, it will downshift and rev up, but it just doesn't go very fast regardless; it just punishes me by sucking up more gas. The tranny doesn't slip and its fluid is at the level it should be. The engine doesn't misfire, kick, stall, or anything. Generally, it seems to run better when it's cold, but I might just be experiencing placebo...

I've made these repairs in (failed) attempts to improve efficiency:
new spark plugs
over-filling tires
K&N air filter

My father's 2.4L '96 Nissan Altima gets 26 MPG and his 2.0L '90 Toyota Camry gets 28 MPG... This is city MPG too, mind you. My engine is smaller than both and it's not getting nearly as much. Or maybe my dad's exaggerating... I dunno.

I hear some people proclaim they get 28 MPG at its lowest and mid-30's MPG normally... Is this really true or is 18-22 city MPG with A/C normal for this car?


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## TheBrownRobert (Aug 28, 2007)

Oh, by the way, when I changed the spark plugs, three of them were beige (indicating normal fuel mixture) and one of them was white. The white spark plug also had a ring of oil burnt around it that seemed to be coming up from where it screwed in (I'm just guessing that's were the oil came from).


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## rbo1577186 (Jan 16, 2005)

No es bueno. Our 94 gets roughly 31 mpg and thats mostly city driving. Engine has over 255k.


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## Tavel (Aug 21, 2004)

we get around 23-24 with the 98 sentra without the A/C. a few MPG lower with AC seems about right. I don't think there's anything wrong with the car, it's just a slow-ass car. Turn the AC on and you're driving like grandpa. (that's partly why we never use AC).

Nissan seems to have especially heavy AC compressors, as turning the AC on in my SE-R (with a 2.0L) slowed it down a lot such that I never used it. 

In my personal opinion, I think the GA16 is undersized for the application. It's too small for the car and has to work at higher RPM's for the same power that a slightly larger engine would pull at low RPM's. 

the 1.6L at 4k RPM burns more fuel than a 1.8L at 2.5k RPM's, even though both are probably getting equal power at those RPM's. Add Nissan's heavy compressors and you get an extremely slow car with poor mileage. 

Not much you can do about that though, shame.


edit: I'll do some math to demonstrate what I'm talking about. 

I can drive my corolla (1.8L) between 2K and 3K quite comfortably. Considering an inline 4 engine cycles its entire displacement every 4 revolutions, the engine cycles 750 times per minute. (3000/4=750). That means it displaces 1350 liters per minute. 

the 1.6L engine operates best between 3K and 4K. So the same math (4000/4=1000), the engine displaces 1600 liters per minute.

since fuel use is proportional to air use, you can see how the 1.6L engine uses a lot more fuel to do the same thing. 

now I understand the engine can't cycle its ENTIRE displacement because of thermodynamic constraints and such...but the principle remains.


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## TheBrownRobert (Aug 28, 2007)

Thanks a bunch for that info! That explains perfectly why 2.0L and 2.4L engines are doing better than my 1.6L with A/C.


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## pare_john (Jul 27, 2007)

i get roughly 35mpg with mixed driving


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## TheBrownRobert (Aug 28, 2007)

I think the key factors involved are the automatic transmission and the use of A/C with city driving. Are the folks getting 30-something MPG equipped with an automatic transmission and use the A/C?


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## pare_john (Jul 27, 2007)

mine is an autotragic but no AC


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## i r teh noobz (Apr 26, 2007)

I only get about 25-28, but thats with AC, Automatic, and very hard driving (and its running pretty rich for some reason....). Alot of mixed driving (city/highway).


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## rbo1577186 (Jan 16, 2005)

We use the AC roughly 20% of the time - not much.


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## ShutUpAndDrive (Aug 18, 2007)

With my Sentra, I was also getting about 33mpg with A/C. It's a manual though so that might make a small difference. I was doing mostly 65mph freeway driving with some stop and go traffic on normal streets 35/45mph.


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## MisterRx (Feb 8, 2006)

I have 92 Sentra E automatic, no AC and I'm aslo getting around 20-23 mpg. I change oxygen sensor, spark plug, fuel filter and air filter without much improvement.

From what I read elsewhere, it sound like Sending Unit is the culprit, located in fuel tank. The sending unit sends the signal of how much gas is left inside the tank on the dashboard. I think there is more gas in the tank then what's indicated.


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## Red_Sentra (Sep 6, 2007)

I have a 1993 Sentra E, 1.6L, 5 speed manual. I get ~ 29-30mpg (city) without A/C. With A/C, the mpg may go down slightly. Since the car is already slow without the A/C, I rarely turn on the A/C, and try my best to open the window (I don't have power window) instead. If it's so hot that I have to turn on the A/C, I may turn it on when stopping, and turn it off when accelerating, and turn it back on when the constant/cruising speed is reached. This is annoying, but people in California tend to drive faster (faster acceleration after turning green light), compared to Wisconsin where I used to live. I don't want to make the drivers behind me very unhappy.


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## Oldnissanguy (Jan 6, 2005)

You've got something wrong Robert. My 94 with auto, air and 183,000 miles gets 26-27mpg worse case around town with the air on; much better in mixed driving.


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## TheBrownRobert (Aug 28, 2007)

I just thought of something... Would incorrect timing cause my symptoms? 'Cause one cylinder is leaner than all the others. I also recently discovered that my front left tire was shredding and had a bulge, so I replaced it. Perhaps the extra rolling resistance caused by that tire may have had some kind of effect...


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## i r teh noobz (Apr 26, 2007)

If only one tire is messed up, you should have your alignment checked, or you will just destroy the new tire.


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## Oldnissanguy (Jan 6, 2005)

Yes, incorrect timing can cause bad gas mileage.


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## lostanfound89 (Apr 30, 2007)

i think my car might have a problem too i drove it to fort bragg nc form Hampton roads va and all of its highway and only got around 28 mpg . i have a 1993 sentra xe automatic with aroud 203000 miles on it ,and i didn't use the a/c on the way cause it was night , i didn't need it . but in the city , when i actually have the cash to fill it all the way up , i use the a/c a lot and get basically the same mileage , sometimes it drops to around 22-23 mpg , and on one occasion 18 but that might be the way i drive idk . but the highway mpg bothers me i know this is not normal . could it be that the speed limit on the way to nc is 70mph (i go 75 - 80 most of the time)????


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## TheBrownRobert (Aug 28, 2007)

I'm not a scientist, but I know that the gas mileage of a car goes way down after 60 MPH. [source]

With 100% city driving and using the A/C most of the time (I live in central Florida), the fuel gauge reads empty at 240 miles, although you can drive it as far as 280 without running out of gas.


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