[M-technik-3]

my 07 N52k was normally 26 to 28 range and just dropped of to an abysmal 20 mpg range and I have changed nothing. I have no soft or hard codes either and last year winter gas was in the 23 range.

Thoughts?

[eljay]

Originally Posted by M-technik-3

my 07 N52k was normally 26 to 28 range and just dropped of to an abysmal 20 mpg range and I have changed nothing. I have no soft or hard codes either and last year winter gas was in the 23 range.

Thoughts?

Rear brake caliper seizing?
Does the car roll freely?

[lordbmw]

26 mpg sounds really good to me.
I average about 16 😆

[ppointer]

mine averages 21.9 measured over the past 2+ years and 16k miles. Some highway trips I see about 26mpg, but all in average is 21.9.

Back when I had an '00 e46it, I noticed a 7% drop when I went from Mich Exalto tires to Mich A/S 3. I use Fuelly to track my mileage over the long haul, btw.

[M-technik-3]

Originally Posted by eljay

Rear brake caliper seizing?
Does the car roll freely?

Might be, I have not had physical time in the day. I work 12 hour shifts and it's nearly winter here in the north east, I just ordered all new pads and rotors and was planning to pull off the summer tires. But I just have not had time lately.

[lookalikehuuh]

26 to 28 MPG is pretty dang good EPA ratings for 328i is "18city 28hwy" so you are at the very top of the estimates with most people reporting a combined 22ish MPG.

If you have been doing more cold starts or in colder weather, it is normal to have lower MPG as car dumps lots more fuel into engine on cold starts to help in the warming of the engine.

[Mosaud1998]

I've been getting poor mileage too. Noticed it after I put Techron in the tank. I usually get around 22-23 MPG. Right now I am getting 18 MPG on a good day.

[eljay]

Originally Posted by lookalikehuuh

26 to 28 MPG is pretty dang good EPA ratings for 328i is "18city 28hwy" so you are at the very top of the estimates with most people reporting a combined 22ish MPG.

If you have been doing more cold starts or in colder weather, it is normal to have lower MPG as car dumps lots more fuel into engine on cold starts to help in the warming of the engine.

I agree.
I'm at 17mpg, but mostly city these days.

[eljay]

Originally Posted by M-technik-3

Might be, I have not had physical time in the day. I work 12 hour shifts and it's nearly winter here in the north east, I just ordered all new pads and rotors and was planning to pull off the summer tires. But I just have not had time lately.

When you change pads/rotros, just service the calipers by cleaning and lubricating the sliding surfaces and you should be OK.

If it's more serious with a caliper piston etc and you don't want to rebuild them, here's a shameless plug: I have low mileage (20k) rear 328xi calipers for sale if needed.

[ctuna]

How many miles on it .
Have you changed plugs ,coils engine air filter.
any difference in how smooth it runs on startup or
down the road?

[Bmw1939]

Originally Posted by eljay

Rear brake caliper seizing?
Does the car roll freely?

Can you elaborate on rolling freely? I have always felt these cars gear down unnecessarily while rolling into a stop.

[E93Dude]

My '07 335 convertible w/6MT weighs more than the sedan or coupe, and gets 29-31 mpg if I am doing leisurely highway driving. But even in normal commuter traffic ("responsible" application of gas peddle, w/ a few hard pulls to pass morons), I am still getting 27 - 28.5. I don't understand how folks, particularly in the NA straight 6s, are getting worse. I do have DCI, but am otherwise bone stock. I was getting slightly worse mileage, but after new plugs/coils and walnut blasting the intakes at 100K, I did notice a noticeable improvement. I also only fill up the car to about 10 gallons at each fill up since that gets me through the week. Gas weighs a little over 6 lbs/gal, so perhaps not hauling around the extra 5-6 gal it would take for a full tank also makes some difference. FWIW, I fill up with COSTCO 91, which is a top tier gas. For those getting poor mileage, make sure you are using the right octane, and are using quality gas.


-- Try driving a little easier.
-- Walnut blast
-- Don't run with a full tank all the time

[M-technik-3]

Originally Posted by ctuna

How many miles on it .
Have you changed plugs ,coils engine air filter.
any difference in how smooth it runs on startup or
down the road?

Plugs are 10K old. I have coils and a VCG just have not installed them. Sounds like I will be turning on furnace in the garage and spending a weekend in there.

Car starts and quickly and idles smoothly and I have 126K

This is an 07 328i e91 with a slushbox and the transmission was serviced by an indie last January as preventative service.

[Pittz1]

26.1 at a steady 75-80mph. My commute is hilly(western MD) with a few straight shots. 06 330xi with 200k miles.

I have a whole new CCV. Plugs are almost at 100k. No leaks.

Even when I do get on it, the worst I get is 25.5 mpg. I am all highway every day.

[eljay]

Originally Posted by Bmw1939

Can you elaborate on rolling freely? I have always felt these cars gear down unnecessarily while rolling into a stop.

I meant when it's on level ground in neutral, you should be able to push the car and get it rolling or feel resistance. Similarly, on a very very slight slope, it should start rolling in neutral (make sure ignition is off or the parking brake assist may engage).

I keep detailed records of fuel economy for all my cars and this is how I was able to catch rear brake caliper seizing on my former B6 Audi Avant and front caliper on my MK4 Golf. In both cases, the fuel economy took a gradual dive until I could literally feel the heat from passenger rear wheel after a drive on the Audi. On the Golf, it was a bit more dramatic as the front caliper seized on the road and started smoking and made it home with brakes on fire. No joke. I felt like a WRC rally driver after completing a competitive stage.

[M-technik-3]

Thinking it was a shit tank of fuel as the car has rebounded back to 25.5 mpg which is consistent with what I got last winter. I know the station that the it came from and will not go back there.

Odd it was a Mobile but maybe older fuel from refinery. Who knows

[JonOhh]

Man ... I'd love to get 20 even.

My average is 16. 330i MT

[M-technik-3]

Originally Posted by JonOhh

Man ... I'd love to get 20 even.

My average is 16. 330i MT

You must be in the throttle all the time. If I am romping on it it quickly drops to low 20's but this car is not my fast road toy its my commuter.

For fun days it's an e30 or e36.

[JonOhh]

Originally Posted by M-technik-3

You must be in the throttle all the time. If I am romping on it it quickly drops to low 20's but this car is not my fast road toy its my commuter.

For fun days it's an e30 or e36.

It hits 7000 rpm at least 5 times a day, yes . However, even when trying to drive in an economical manner (shifting 2500rpm or lower, very light acceleration, no AC when possible, engine braking well ahead of stopping zones) I still barely manage to eek out 20 in the city.


My brakes drag a tiny tiny bit. If I am rolling to a stop off the brake pedal I feel an ever so slight bump as I come to a stop (indicating a level of resistance to roll). However, this didn't change after a brake change and after greasing caliper pins, so maybe this extremely slight amount is normal?

Also, I do not mean to thread jack but answers to this could potentially be helpful to the threads main question, for others.