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DISCUSSION => General Topics => Topic started by: Deutschbag on September 17, 2006, 08:15:54 PM

Title: 22 mpg? Why?
Post by: Deutschbag on September 17, 2006, 08:15:54 PM
So I got like 19mpg last time about a month ago when I filled up. I figured it's because I just got the car and have been having too much fun shifting at 6500 rpm here and there, flooring it to hear how the engine sounds, using the AC because I've never had a car w/ AC in it, etc. This month, I've been driving like a grandma and opening the windows, and I only upped my mpg to about 22 or 23mpg, and I've been doing like 50/50 street & highway driving. This is absolutely unacceptable for a 4 cylinder car, if I'm not gonna have the power of the m20 I might as well at least get better mileage! I got 30mpg in my modified 2L Jetta (full exhaust & header, 270 degree camshaft w/ a chip to match, close ratio Scirocco tranny) and I drove it hard.

So the car is bone stock, no check engine light or anything. Where should I begin to look for problems? O2 sensor? I'm gonna replace the fuel filter when I get a free moment too, I've already bought one. Anyone else remedy any bad mileage problems lately? Thanks fellas!

Pic of the old jetta and the new 318is, needing a front valence badly (talk to me if you have one for sale!)

(http://i10.photobucket.com/albums/a148/hogborg/symbolism.jpg)
Title: 22 mpg? Why?
Post by: m42 fan on September 17, 2006, 09:16:43 PM
I'd go ahead and do a complete tune up, especailly if you don't know when it was done last.  Prety much all the things you already mentioned.  Filters, O2, plugs and wires couldn't hurt either.

Also, all BMW Odometers read lower than actual mileage.  Meaning you are traveling farther than you think you are.  Meaning you are getting better mileage than you think you are.  Take the car out on the freway and hit the trip odometer when you pass a milepost.  On the 10th milepost, check your trip to see how far off it is.

hth

Brian
Title: 22 mpg? Why?
Post by: D. Clay on September 17, 2006, 11:31:19 PM
I get 26 - 27 MPG. I've never checked the odometer though. I've heard of big top speed numbers too, but I'd take a snack in case I got hungry getting up there.
Title: 22 mpg? Why?
Post by: Tonyb on September 17, 2006, 11:53:35 PM
Bad converter?
Title: 22 mpg? Why?
Post by: dbgrubbs on September 18, 2006, 05:09:29 AM
I checked my odometer with a GPS and it was 10% off.   Ex: The odometer would show 300 miles but the GPS was showing 330 miles. Something to consider when checking your gas mileage. The speedometer was also optimistic by 4 mph.
Title: 22 mpg? Why?
Post by: ak96ss on September 18, 2006, 09:20:45 AM
Maybe it's because you have a Volkswagen emblem on a BMW?

;)

According to the EPA website, the 1991 318is was rated 22 MPG city and 27 MPG highway.

Sounds like you are right in the ballpark for that car when it was new.

I didn't buy the 318is because it got good mileage, although it is better than my other cars. And I didn't buy it for the power (that's what the Daytona is for with 350 HP and 390 lb-ft). I bought it because I needed a commuter car, and the 318is is a hoot to drive.

Having said all that, a tune-up couldn't hurt, but you aren't going to see 30 MPG unless you baby it and stick to the highway.

FWIW.
Title: 22 mpg? Why?
Post by: dbgrubbs on September 18, 2006, 10:18:24 AM
Quote from: ak96ss
Maybe it's because you have a Volkswagen emblem on a BMW?

;)

According to the EPA website, the 1991 318is was rated 22 MPG city and 27 MPG highway.

Sounds like you are right in the ballpark for that car when it was new.

I didn't buy the 318is because it got good mileage, although it is better than my other cars. And I didn't buy it for the power (that's what the Daytona is for with 350 HP and 390 lb-ft). I bought it because I needed a commuter car, and the 318is is a hoot to drive.

Having said all that, a tune-up couldn't hurt, but you aren't going to see 30 MPG unless you baby it and stick to the highway.

FWIW.


I totally agree with this. And don't pay attention to the posts that claim 35 mpg out of the 318is. I don't believe for one minute that this is possible with the stock rearend. 30-32 being babied on the highway is about the best you'll get. I average about 27 mpg in mixed driving and this takes into account the odometer error. I've always been able to top the EPA rating in all my previous cars too. Hard to do with this one.
Title: 22 mpg? Why?
Post by: Alpine003 on September 18, 2006, 10:54:27 AM
When I first got my car recently, it was avging 22mpg. I since then replaced faulty O2 sensor, ignition wires, and spark plugs and get 26mpg consistently. My drive is 50% highway(going 75-80mph), and 50% rush hour bumper to bumper traffic. I try not to take it over 3k rpm during acceleration to save on fuel.

I also don't believe anyone that claims 35-40mpg either(at least with a factory rear end).
Title: 22 mpg? Why?
Post by: Alpine003 on September 18, 2006, 10:56:30 AM
Quote from: m42 fan

Also, all BMW Odometers read lower than actual mileage.  Meaning you are traveling farther than you think you are.


Is this true across the board for all 318is models? Or is there some kind of faulty batch of instrument clusters out there? Very interesting and I'll have to check mine.
Title: 22 mpg? Why?
Post by: automatic on September 18, 2006, 11:02:38 AM
I just burned through my first full tank of gas and got 27mpg with about 50/50 highway/city driving. I was hoping for closer to 30 but if the odo is infact 10% off then i'm doing good.
Title: 22 mpg? Why?
Post by: dbgrubbs on September 18, 2006, 11:07:58 AM
Don't know if all the odometers are off or not. Just that mine was. Seemed weird that my odometer was reading low and the speedometer high. It's worth checking your accuracy though if it helps you sleep better at night.:)  I do!
Title: 22 mpg? Why?
Post by: soks86 on September 20, 2006, 02:05:28 PM
Under 3k rpm for acceleration...

I must drive like a granny... I almost always shift under 2.5k (usually under 2.3k) and I get about 29MPG with about 50/50 highway/urban CHICAGO driving. Not to say I spend half my time on the highway either, it's just that when I do hit the highway I go fast... LOTS of urban driving though.
Title: 22 mpg? Why?
Post by: dino245 on September 20, 2006, 02:42:14 PM
I drive like a crazy person and do about 50/50 driv ing and get 28mpgs and 31if all I do is hwy
Title: 22 mpg? Why?
Post by: bmwman91 on September 20, 2006, 04:23:30 PM
I usually pull 22ish around town driving somewhat fast, 27ish when behavnig.  Highway...30ish if I am going 85-100, 36ish if I stay under 80.
Title: 22 mpg? Why?
Post by: Choking Hazard on September 21, 2006, 03:12:51 PM
Well...
I was one of those folks that ranted about phenomenol mileage.  I think I was delusional because whenever I looked at the mileage meter, it was reading 25 or more MPG.  Of course, when I wasn't driving like Grandma, I wasn't looking at the meter either.  After several tanks and many highway and city miles, I've decided I get about 25 mpg average.  I can get 25 in traffic with some effort, but I am an impediment to traffic then.  At 55 to 60 mph, the meter indicates 30, and that may be close to right.  At 70 mph, it drops, and at 80 mph it drops more- indicating about 20 mpg.  I think the car is tuned for highest efficiency at 55 mph.
Title: 22 mpg? Why?
Post by: Alpine003 on September 21, 2006, 04:17:28 PM
Quote from: soks86
Under 3k rpm for acceleration...

I must drive like a granny... I almost always shift under 2.5k (usually under 2.3k) and I get about 29MPG with about 50/50 highway/urban CHICAGO driving. Not to say I spend half my time on the highway either, it's just that when I do hit the highway I go fast... LOTS of urban driving though.


For the guys getting 28+ mpg, do you have stock wheels/tires? and how many miles do you have on your car?
Title: 22 mpg? Why?
Post by: Deutschbag on September 21, 2006, 09:58:49 PM
Good info, pretty much what I expected. I'm gonna go ahead and do the plugs + wires and O2 sensor when I get some cash. I just did the rear diff oil and it was a breeze, quieted down that LSD quite a bit.
Title: 22 mpg? Why?
Post by: individualist on September 22, 2006, 05:48:57 AM
I have stock wheels, well stock everything with 196,000+ on the odometer. I run 87 octane, 75% highway driving and I consistantly get 29 to 30 mpg. I don't tax this car at all on takeoff or any other time, just normal driving 70 to 80 mph. I bought this car 4 months ago for $350 just for economy as my other vehicle is a 04 Lariet with a 5.4L, supercrew 4X4 that gets 16mpg if I baby it. I wasn't looking for a 318is it just kind of fell in my lap and now it's really grown on me. My family thinks I'm nuts for parking my truck and at first wouldn't ride in it. Now that I've put a beefed up sound system in it they seemed to have lowered their standards a bit.
Title: 22 mpg? Why?
Post by: twinpop171 on September 22, 2006, 06:33:06 AM
Quote from: bmwman91
I usually pull 22ish around town driving somewhat fast, 27ish when behavnig.  Highway...30ish if I am going 85-100, 36ish if I stay under 80.



This is about the same for me.  Stock weaves and tires, 134k, I run 93 octane.  I beleive that I've got a 3:73 open diff. in mine though BTW.

I'd do the tune up you are planning and also clean the air intake system, idle control valve and check/replace the notoriously bad vacuum lines.  Do a search here for that.

Good luck and keep us posted, Dan.
Title: 22 mpg? Why?
Post by: automatic on September 22, 2006, 10:11:25 AM
Quote from: individualist
I have stock wheels, well stock everything with 196,000+ on the odometer. I run 87 octane, 75% highway driving and I consistantly get 29 to 30 mpg. I don't tax this car at all on takeoff or any other time, just normal driving 70 to 80 mph. I bought this car 4 months ago for $350 just for economy as my other vehicle is a 04 Lariet with a 5.4L, supercrew 4X4 that gets 16mpg if I baby it. I wasn't looking for a 318is it just kind of fell in my lap and now it's really grown on me. My family thinks I'm nuts for parking my truck and at first wouldn't ride in it. Now that I've put a beefed up sound system in it they seemed to have lowered their standards a bit.


Car runs ok on 87 octane?

Quote from: twinpop171
This is about the same for me.  Stock weaves and tires, 134k, I run 93 octane.  I beleive that I've got a 3:73 open diff. in mine though BTW.

I'd do the tune up you are planning and also clean the air intake system, idle control valve and check/replace the notoriously bad vacuum lines.  Do a search here for that.

Good luck and keep us posted, Dan.


I am on my second tank of gas and I got 28.8 mpg. I also checked the accuracy of my odometer and it appears to be right on.

My suspicion is that those with odometers that are reading 10% off is that they have wheels/tires in a different size then stock.
Title: 22 mpg? Why?
Post by: Alpine003 on September 22, 2006, 10:38:41 AM
Quote from: individualist
Now that I've put a beefed up sound system in it they seemed to have lowered their standards a bit.


You mean raised their standards? :p
Title: 22 mpg? Why?
Post by: dbgrubbs on September 22, 2006, 11:34:28 AM
Quote from: automatic
Car runs ok on 87 octane?



I am on my second tank of gas and I got 28.8 mpg. I also checked the accuracy of my odometer and it appears to be right on.

My suspicion is that those with odometers that are reading 10% off is that they have wheels/tires in a different size then stock.



This is true in my case but then why would the odometer be reading less than the actual mileage and the speedometer be reading high? Seems as though if the odometer was too low, the speedo would be too. Just not the case. And 10% low on the odometer from one size up? Don't think so.
Title: 22 mpg? Why?
Post by: nickmpower on September 22, 2006, 02:50:09 PM
I saw over 30 per tank with some freeway and some city, week after week
Title: 22 mpg? Why?
Post by: tim_s on September 22, 2006, 04:20:39 PM
i know different continent, different temps, different fuel (95RON), but 35mpg on motorway runs is no probs. 30mpg around town. not sure why such a large difference, its an interesting one!
Title: 22 mpg? Why?
Post by: dino245 on September 22, 2006, 04:53:23 PM
tim s I think one thing needs to be clearafied. A US gallon is smaller than the UK or imperial gallon. So you would naturaly get a better milage calculation.
Title: 22 mpg? Why?
Post by: dino245 on September 22, 2006, 04:58:33 PM
I found this conversion 1Gallon(uk)=4.546 liters   1Gallon(US Liquid)=3.785 liters
Title: 22 mpg? Why?
Post by: individualist on September 23, 2006, 07:37:57 AM
Quote
Car runs ok on 87 octane?


I know you are supposed to run higher octane rating but I just never have. Car runs great on 87, been running it for 4 months now.

Quote
You mean raised their standards?


Yeah, my daughter says it looks ghetto, just yesterday I took the day off from work (comp time) and went out to the 318 to give her a ride to school and she asked "are we taking that"? I said what's wrong with it? She had no reply so I figured she felt she'd be stoned by her peeps as soon as she steps out of it at school. So we jumped in my wifes car and off we went. I guess she'll go just about anywhere in it BUT school.
Title: 22 mpg? Why?
Post by: Katz Tsubai on September 23, 2006, 02:01:33 PM
Quote from: dbgrubbs
This is true in my case but then why would the odometer be reading less than the actual mileage and the speedometer be reading high? Seems as though if the odometer was too low, the speedo would be too. Just not the case. And 10% low on the odometer from one size up? Don't think so.


It is unlikely, but is there any chance that speedo and odometer operate independently on these cars?  

One time, the odometer on my beater '85 318 quit working momentarily for about 15~20 miles.  The speedo functioned properly all the while.

On my '91, I currently run 225/50R15s.  Their loaded radii are within fraction of inches to that of stock tires.  Speedo is still off (as if the tires are small), but odometer is pretty accurate according to GPS.

My car averages about 25mpg, 60/40 city/highway.
Title: 22 mpg? Why?
Post by: Vladi on September 24, 2006, 09:00:35 AM
This is what i usually get driving out of town. It's in liters/100km, i don't know to convert it to miles/gallon.:rolleyes:
Title: 22 mpg? Why?
Post by: silverblades181 on September 24, 2006, 03:28:22 PM
6.6L/100km is awesome....the best I did was 7.8L/100km and that was on the highway...I did 9L/100km driving around town and 13L/100km on the track. I think my 02 sensor was busted though
Title: 22 mpg? Why?
Post by: automatic on September 27, 2006, 01:53:49 PM
Quote from: Katz Tsubai
It is unlikely, but is there any chance that speedo and odometer operate independently on these cars?  

One time, the odometer on my beater '85 318 quit working momentarily for about 15~20 miles.  The speedo functioned properly all the while.

On my '91, I currently run 225/50R15s.  Their loaded radii are within fraction of inches to that of stock tires.  Speedo is still off (as if the tires are small), but odometer is pretty accurate according to GPS.

My car averages about 25mpg, 60/40 city/highway.



It is fairly common to see a broken odometer and a working speedometer so that would make me think they do work independently.
Title: 22 mpg? Why?
Post by: tmorinbmw on October 03, 2006, 07:49:51 AM
I've taken plenty of e30's apart and know for a fact that the odometer and speedometer don't work individualy, not supposed to anyway. If there are decrepencies between the two then check the white plastic gears that drive the two. Over time they grow brittle and loose teeth resulting in miss-readings and not functioning all together.

They're replacable, check Bavauto or someplace like that.
Title: 22 mpg? Why?
Post by: tim_s on October 03, 2006, 08:17:26 AM
Quote from: dino245
tim s I think one thing needs to be clearafied. A US gallon is smaller than the UK or imperial gallon. So you would naturaly get a better milage calculation.
oh yeah, oops! I'll shut up then