22 mpg? Why?

[Deutschbag]

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!)

[m42 fan]

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

[D. Clay]

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.

[Tonyb]

Bad converter?

[dbgrubbs]

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.

[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.

[dbgrubbs]

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.

[Alpine003]

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).

[Alpine003]

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.

[automatic]

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.

[dbgrubbs]

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!

[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.

[dino245]

I drive like a crazy person and do about 50/50 driv ing and get 28mpgs and 31if all I do is hwy

[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.

[Choking Hazard]

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.