Gas Mileage revisited...

[QuickSilverGT]

Well I had posted about getting some pretty crappy gas mileage before (21mpg, city). Just over a month ago I got my first CEL at (58k). Took it to the dealer and they replaced an o2 sensor. Didn't fix it so I took it back. They replaced the another 02 senor. Since that time my gas mileage has jumped to 26mpg. Don't know why my o2 sensor went bad so quickly but I got both replaced for free under warranty and I'm now am getting much better gas mileage now. I haven't made a single other change to my car.

[BlackElantraGT]

I was considering changing the O2 sensors on my car also since it's more than 72K miles now, but according to some sources, with the 2nd generation heated O2 sensors, they generally don't need replacement until after 100K miles.

My fuel mileage went up tremendously on my old 92 Sentra when I changed its O2 sensor for the first time at around 130K miles.

[jayupark]

I think I read it on here somewhere... but I can't find it (searched). Anyone know how to safely clean an O2 sensor? (if it's possible). Thanks.

[BlackElantraGT]

I've never heard of cleaning an O2 sensor. It's just one of those things you replace... like a spark plug, just not as often of course.

[QuickSilverGT]

I'd sure like to know why my o2 sensors only lasted 56k. The one on my civic lasted a bit over 100k.

[exsailor]

My O2 sensor in second bank went at 15000kms (9000 miles) :(

[PJB]

26 mpg still isnt good unless youre beating on it. My car regularly gets 32 mpg.

[Cypher]

i regularly get 33mpg. on the way back from florida i got 35mpg and right now i'm at 440 miles on this tank of gas and the light isn't on yet ;)

[BlackElantraGT]

I could be wrong, but didn't some of you mention the Elantra runs a bit rich? If that's the case, maybe that's the reason for the premature failures of the O2 sensor because supposedly the 2nd generation heated O2 sensors should last until 100K miles.

[Cypher]

hey guys i filled up my gas tank today. i had 441.6 miles on it and it took 11.89 gallons to fill it up. thats 37mpg;)

[WytchDctr]

Elantras (Beta2s anyway) run lean until 4k then run rich. I get about 30mpg avg with mixed driving and as much as 35mpg on the highway and I never drive slow.

[ArunSenior04]

Man, Ive managed to get near 40mpg driving nicely. Plus, the Tib gas guage helps alot. Whener I see the needle going under 32mpg, I deaccelerate.

[Cypher]

fully modded i hit 36.5mpg at a constant 80mph on the way back from evan's. boo yah!

[robs02elantra]

hey guys i filled up my gas tank today. i had 441.6 miles on it and it took 11.89 gallons to fill it up. thats 37mpg;)

I may look stupid, but I'm tired so leave me alone. Knowing how far you went, and how much it took to fill, how do you get the mpg?

[Cypher]

i always fill up my tank and always reset my trip. therefore when i fill up again i take the miles travelled divided by how many gallons it took to fill it up. thus miles/gallon

[04GTboySC]

my car shows the mpg on the trip computer :-P im getting about 36 mpg with the intake manifold just installed

[Cypher]

that doesn't count scott.

[robs02elantra]

i always fill up my tank and always reset my trip. therefore when i fill up again i take the miles travelled divided by how many gallons it took to fill it up. thus miles/gallon

you see, and that makes sense to me. I just thought I remembered that someone had said it wasn't an accurate way to measure mpg. Can't remember who, when or where, but I think it was on the site here somewhere. Anyway, I'm going to get my mileage book out of the car when my wife gets home to see what my averages have been.

Back on topic, which 02 sensor did you have replaced?

[BlackElantraGT]

Cypher, what size are your tires?

[paki]

i get about 25.5-26 mpg and thats while beating on it most of the time and AC running. I need to see how much mileage I can get just driving normally.. but i can't stop my foot from smashing the pedal to the floor.. damnit! lol

[Cypher]

Cypher, what size are your tires?

205/50/15s

[BobMs_wht2k2]

Well, afterfinding out that my tire size affects my speedo by 8% instead of my previously thought 4%. . . I'm getting 32-35mpg at 75-85mph.

[BlackElantraGT]

205/50/15s

Your wheel/tire setup is 4.7% smaller than the stock setup, which means that you didn't do 441.6 miles but rather 420.8 miles, which makes your mpg more like 35 mpg.

35 mpg is still impressive for the XD, but then again those are all highway miles. I've been able to hit those numbers too when it was strictly all highway at moderate speed using cruise control. It's also very hard to compare mileage because terrain can play a huge role. You might be able to get 35 mpg one way, but most likely in the XD, you wouldn't be able to get that going the other way. Plus, in some populated area, you may be driving highway, but the highway may be too congested to use cruise control, which I think helps the fuel economy quite a bit too.

But since I've driven off the car brand new off the lot, it's always gotten horrible mileage in the city. As far as everyday driving with about 60 city/40 highway, I used to get between 23-25 mpg. Now with mostly city driving, it's more like 18-21 mpg.

[Cypher]

i didn't think the smaller tire size actually threw off the odometer.

[BobMs_wht2k2]

Physics don't lie. . . plus I noticed that our speedos tend to read a little faster than our actual speed to start with. Trying to burn up that warranty a little fasteR?

[Cypher]

That, in no way/shape/form, will affect your tach signal. The only thing it will effect is your actual vehicle speed.

referring to me saying something just like that. hes a tech. i believe him.

[BobMs_wht2k2]

Correct, and by affecting the vehicle speed it affects actual miles driven.

[Cypher]

eh whatever

[BlackElantraGT]

referring to me saying something just like that. hes a tech. i believe him.

Notice how he says it affects the TACH. He even says it affects the speed of the vehicle, which is why your speedometer will be incorrect due to your smaller tire size. The tach has no part in your mpg calculation.

[ArunSenior04]

Wow that makes perfect sense. I never realized that.

[Cypher]

yeah i know. sorry. brain lapse. i was rushing between trying to type and fixing the ignition oven at work. ugh.