Gas mileage?

[ohnoes]

Hi all, I'm new to 1addicts but have been posting a bit on the other forums in this community (mostly E90post) for a bit.

I just bought my CPO'd 135i last week and am enjoying the car, though it is certainly a lot different than the E46 M3 I came from. I do love the torque of the N54 throughout the powerband! Anyway, I'll save the comparo for another thread.

My main concern right now is with the gas mileage. The OBC is currently showing 17.4ish MPG, and that is with a 60% city/40% highway split. My substantially modified M3 consistently did 1MPG+ better than that (18.6-18.9).

Is this normal or is something possibly wrong with my car? Please advise, as the small gas tank combined with this crappy gas mileage is rather irritating.

[Tom K.]

Is the car fully broken in (at least 3k miles)? Are you resetting the BC each tankful? And have you checked the BC accuracy against the measured mpg over at least 3 tanks?

While I generally manage to stay out of DC area traffic, my worst is about 21 and I average 28+ on the road in my 128i. From what others have reported, the 135i should consume about 15~20% more fuel - depending on one's right foot.

And I agree, the tank is small - but I wouldn't give up any trunk space, especially on a 'vert.

Enjoy your new 135i!
Tom

[zerbitini]

I just filled up for the first time in my new 135icp, manual transmission. 338 miles and 13.37 gallons = 25.3 mpg. That's 85% highway and 15% city... but I took it easy and only REALLY accelerated a couple times with that first tank of gas. My last BMW improved 2 mpg between the first tank and the average over the next 92,000 miles... so I'm anticipating 27 mpg before long. How you use your right foot is the main factor.

[gargoyal]

If you are "enjoying" your car and you have a manual tranny, yes. A heavy foot and higher revs (more boost) burns gas fast. I drive about the same mix and was averaging 16.6 -18 mpg when I first got my 135. I was uses to a high revving car so I kept it in lower gears at higher revs. That was a big mistake for gas mileage , though lots of fun for dusting people on lane changes.

I had to learn how to drive the car for fuel efficiency. I did this by watching the computer while driving. In general, keep it at low revs it the highest gear that make sense and get to 6th asap on the freeway. You will learn to drive two different ways one for fun and one for fuel.

[ohnoes]

I don't have any more of a lead foot than I did in my E46 M3--as a matter of fact, probably less--yet my gas mileage is worse... and given the N54's abundance of low-end torque, this seems quite odd. I'm well past break-in, as I bought the car CPO'd with over 25k miles. I now have 26k as of yesterday. It's only had one oil change/service, so perhaps the air filter is clogged or something. I also notice that the throttle response is poor and there is significant turbo lag, despite the dealer saying I have the latest "lag-fix" software (v34). It is definitely laggier than the 5 or so 335s I've driven...

[ohnoes]

Originally Posted by gargoyal

If you are "enjoying" your car and you have a manual tranny, yes. A heavy foot and higher revs (more boost) burns gas fast. I drive about the same mix and was averaging 16.6 -18 mpg when I first got my 135. I was uses to a high revving car so I kept it in lower gears at higher revs. That was a big mistake for gas mileage , though lots of fun for dusting people on lane changes.

I had to learn how to drive the car for fuel efficiency. I did this by watching the computer while driving. In general, keep it at low revs it the highest gear that make sense and get to 6th asap on the freeway. You will learn to drive two different ways one for fun and one for fuel.

I do try to keep it in the highest gear possible while commuting. I am not so much worried about absolute fuel consumption, but I think there's something strange about a car with as much low-end torque as the N54 has getting such crappy gas mileage, where my 360hp/275tq E46 M3 needed to be revved to 6,000rpm to get any real grunt, yet it got 1mpg+ better mileage.

My OBC is now showing 17.2mpg.

[gargoyal]

Originally Posted by ohnoes

I don't have any more of a lead foot than I did in my E46 M3--as a matter of fact, probably less--yet my gas mileage is worse... and given the N54's abundance of low-end torque, this seems quite odd. I'm well past break-in, as I bought the car CPO'd with over 25k miles. I now have 26k as of yesterday. It's only had one oil change/service, so perhaps the air filter is clogged or something. I also notice that the throttle response is poor and there is significant turbo lag, despite the dealer saying I have the latest "lag-fix" software (v34). It is definitely laggier than the 5 or so 335s I've driven...

hmm, that doesn't sound right. do you have issues starting the car? I dont think HPFP problems cause gas milage issues, but we blame it for everything else. also 3500 rpm is high on the 135 if you are going for gas milage.

[gargoyal]

Originally Posted by ohnoes

I do try to keep it in the highest gear possible while commuting. I am not so much worried about absolute fuel consumption, but I think there's something strange about a car with as much low-end torque as the N54 has getting such crappy gas mileage, where my 360hp/275tq E46 M3 needed to be revved to 6,000rpm to get any real grunt, yet it got 1mpg+ better mileage.

My OBC is now showing 17.2mpg.

The low end torque comes from the turbos kicking in so early. the boost from the turbos sucks up fuel. We start building up boost low in the rev band. NA cars don’t have the same issues. (E46 is NA). With a single turbo like an evo, it is easy to stay out of boost and get good gas mileage. the 135 starts building boost at less than 2000 rpms. When you get more boost you put more air and fuel into the cylinder, this is where you get the extra power and torque (and fun ), but decreases gas mileage

A soft foot and a high gear make a real difference

[aarong_m3]

21-22mpg 60% highway/40% city. I have 82xx miles on the car. Break in oil change at 2000 miles and the next one at 9000 miles.

[ohnoes]

Originally Posted by gargoyal

hmm, that doesn't sound right. do you have issues starting the car? I dont think HPFP problems cause gas milage issues, but we blame it for everything else. also 3500 rpm is high on the 135 if you are going for gas milage.

No long starts thus far--probably started it at least 100 times so far.

Originally Posted by gargoyal

The low end torque comes from the turbos kicking in so early. the boost from the turbos sucks up fuel. We start building up boost low in the rev band. NA cars don’t have the same issues. (E46 is NA). With a single turbo like an evo, it is easy to stay out of boost and get good gas mileage. the 135 starts building boost at less than 2000 rpms. When you get more boost you put more air and fuel into the cylinder, this is where you get the extra power and torque (and fun ), but decreases gas mileage

A soft foot and a high gear make a real difference

I just don't think 17.2 mpg is, or should be, normal. I'd like more empirical info for what people are getting on average. Of course, driving styles vary, but even with semi-aggressive driving I think it sounds low.

[ohnoes]

Originally Posted by aarong_m3

21-22mpg 60% highway/40% city. I have 82xx miles on the car. Break in oil change at 2000 miles and the next one at 9000 miles.

That mileage sounds more reasonable.

Any ideas on what I should check, or what it might be if I bring it in to the dealer, who might very well say "it's normal?"

[kingnonis]

Originally Posted by ohnoes

That mileage sounds more reasonable.

Any ideas on what I should check, or what it might be if I bring it in to the dealer, who might very well say "it's normal?"

16.5 mpg is about as good as it gets for me dude. But i do about 90% city driving though and drive like a psycho, so i guess that might explain it.

[ohnoes]

Originally Posted by kingnonis

16.5 mpg is about as good as it gets for me dude. But i do about 90% city driving though and drive like a psycho, so i guess that might explain it.

And you have JB+ and a 'vert...

[RPM90]

Originally Posted by ohnoes

No long starts thus far--probably started it at least 100 times so far.



I just don't think 17.2 mpg is, or should be, normal. I'd like more empirical info for what people are getting on average. Of course, driving styles vary, but even with semi-aggressive driving I think it sounds low.

How many total miles have you driven?

My new 135i has about 430 miles on it. My current computer calculated mileage is 21.2mpg. However, I rely on the tried and true mathematical method, which is to 0 the miles, fill up the tank and STOP when the auto shutoff stops. Drive the mileage. For me, that means I wait until I get to at least under 1/4 tank. I fill up again, and STOP when the auto shutoff stops. I take the previous miles driven and divide by the gallons I just put in. I then compare that to what my computer says, and over time you'll get a much more accurate knowledge of your MPG.

Most of my driving is "highway-ish". I don't live in a city type area with lots of stop and go in short intervals. However, there are a lot of lights with longer stretches in between, and it depends on when you hit the lights.

My last car, a 2006 A4 2.0T quattro 6spd man. gave me about 23-24mpg, calculated, on average driving. The comp showed more like 25-26mpg.
On longer highway drives my comp would show 30-31mpg, with real calculated mpg being lower.

Before that, I had a 2003 325i sport 6spd man. and my calculated MPG was about 22-25mpg (changed a LOT in cold weather).
Computer was a tad optimistic. The Audi's comp was VERY optimistic.

If I can get about 20-21mpg on my 135i, average, and still drive it like I did the A4 and 325i that will be excellent.
I expect the mpg to go up once the engine "loosens up" a bit with more miles, as my A4 and 325i did.
So far, I've been driving mildly for most of my short miles. I have made a number of runs to redline though, and I tend to cruise on the highway between 70-80mph.
I LOVE how flexible this engine is. You can get best MPG by shifting around 2000rpm, and even "skip shifting" every other gear to get to 6th asap. My 2.0T A4 turbo didn't like 5th under 40mph or 6th.
My 135i doesn't seem to mind at all.

Still, low revving this type of engine over and over is not a good thing.
High performance engines, and most engines really, don't like to be constantly driven at low rpm. You have to get on it every once in a while and get things ripping up near redline to keep internals clean.
So at times, MPG be damned!

[TP 135i]

With 15K miles on my 135, I have averaged 24.2 mpg since brand new.
I drive 90% mature adult and 10% wild person.

[RPM90]

Originally Posted by ohnoes

That mileage sounds more reasonable.

Any ideas on what I should check, or what it might be if I bring it in to the dealer, who might very well say "it's normal?"

It's really quite variable.
What type of terrain do you drive on; hilly or flat?
How do you accelerate?
What pressure do you run your tires at?
How often do you have passengers?
Do you carry any weighty items with you often?
Do you do a lot of "rev matching"?
Do you idle a lot?
It really comes down to, "it depends."

I notice you say that you've to quite a bit of lag.
How much? In my 135i I notice pretty much no lag, and I am very familiar with turbo lag. I've owned a 1981 Audi 5000 turbo, a Mits Eclipse Turbo, and a 2.0T FSI A4, and now the 135i. Each of those vehicles had less and less lag. The 135i has less than the A4 did, but that's also due to the 135i larger 3.0 liter 6cyl to begin with, and then 2 not very large turbo's.
I wonder if perhaps you've got a small leak somewhere?
Check your intake, including the hoses routing to the IC's (intercoolers).
It's always a possibility that somewhere one of the clamps is a bit loose.
However, that will usually show up as boost builds up and then power seems to dip. But, if you're driving with light throttle, even a light leak could lead to some lag.

As you mentioned as well, check the air filter too, to make sure it's fresh and breathing well.

[ohnoes]

Thanks for the info, guys. I haven't checked tire pressure yet (rear tires are brand new, replaced and mounted/balanced by the dealership), but I will. I drive fairly aggressively, not insanely, but definitely spiritedly. Do rev-match, but don't heel/toe much in this car yet; takes some getting used to compared to my M3, and I'm still learning the rest of the car. Usually there are no passengers and no other objects in the car.

I don't think I want to dig around in the insanely complex engine bay too much, but I'll check out the air filter and visible hoses. That seems like the most logical place to start (combined with tire pressure). I have a feeling that if neither of those turns up anything, the dealer will just dismiss my concerns by saying it's normal.

[aarong_m3]

Not sure what you should check(Fuel filter, Fuel pump). The 21-22mpg i get is 25% in Sport mode and 75% Normal mode. I drive aggressive 40% of the time and floor it when needed or if some jerk wants to pull up on me. I also have JB2 with BMS single cone intake. I've even done Autocross and still manage 20.5-21mpg. How many miles do you get when the fuel light turns orange? If you get above 260miles then your good.

On my 2002 M3 i managed 19.2-19.7mpg all the time. The only mods i had was drop in filter, lowered and CCWHEEL Forged 19in wheels.

Good luck.

Originally Posted by ohnoes

That mileage sounds more reasonable.

Any ideas on what I should check, or what it might be if I bring it in to the dealer, who might very well say "it's normal?"

[RPM90]

Originally Posted by ohnoes

Thanks for the info, guys. I haven't checked tire pressure yet (rear tires are brand new, replaced and mounted/balanced by the dealership), but I will. I drive fairly aggressively, not insanely, but definitely spiritedly. Do rev-match, but don't heel/toe much in this car yet; takes some getting used to compared to my M3, and I'm still learning the rest of the car. Usually there are no passengers and no other objects in the car.

I don't think I want to dig around in the insanely complex engine bay too much, but I'll check out the air filter and visible hoses. That seems like the most logical place to start (combined with tire pressure). I have a feeling that if neither of those turns up anything, the dealer will just dismiss my concerns by saying it's normal.

I was thinking a bit more, and I remember that there was an early issue with some 135i wastegate actuators. Mosty, I believe, they were rattling.
But, I would still check to see if perhaps you may have one of them stuck a bit open and fully closing as it should. That could explain a greater sense of "lag" as a not fully closed wastegate would simply be loosing boost before enough pressure builds to overcome the small leak.
You would feel that as a greater lag.

I asked about the rev matching, because you are throttle blipping to do this, and any time you blip that throttle you're using fuel. In the rev match scenario you're using some fuel to go no where really, just to spin the engine up to match the rpm for the lower gear.

The heel/toe is a bit odd on this car, I agree. My 325i had a better setup.
The plane of the throttle and the brake seem a bit off, and it "feels" like the brake is a bit too far to the left.
In a heel/toe, you're still rev matching, but in a more controlled way as you control the throttle in a steadier fashion to balance the braking, gear change, and turn.
It just takes a bit more time due to how the pedals are placed, but it starts to feel ok when you get more used to it.
I do wish the pedals had a more natural placement though, as it would cause me to heel/toe more often.

[CrazyIvan]

I say, screw the mileage. It all depends on your driving style, road conditions, tire inflation, etc. But what do you expect from 300hp car? If you want great mileage, buy a Prius or diesel. I get low 20's in town mix. Doesnt bother me a bit, but it sure is fun to dust all kinds of people

[RPM90]

Originally Posted by aarong_m3

Not sure what you should check(Fuel filter, Fuel pump). The 21-22mpg i get is 25% in Sport mode and 75% Normal mode. I drive aggressive 40% of the time and floor it when needed or if some jerk wants to pull up on me. I also have JB2 with BMS single cone intake. I've even done Autocross and still manage 20.5-21mpg. How many miles do you get when the fuel light turns orange? If you get above 260miles then your good.

On my 2002 M3 i managed 19.2-19.7mpg all the time. The only mods i had was drop in filter, lowered and CCWHEEL Forged 19in wheels.

Good luck.

I do like simply drop-in filters like a K&N. I've always seen a bit of increase in mpg with them.

What drop-ins have you seen for the 135i?
I used a "Green" brand drop in for my A4. It was a very nicely made filter.
I looked very much like a K&N except with better build quality, and green oil instead of red. I'm guessing that's why they called them "Green".
I are smart.

[ohnoes]

Originally Posted by aarong_m3

Not sure what you should check(Fuel filter, Fuel pump). The 21-22mpg i get is 25% in Sport mode and 75% Normal mode. I drive aggressive 40% of the time and floor it when needed or if some jerk wants to pull up on me. I also have JB2 with BMS single cone intake. I've even done Autocross and still manage 20.5-21mpg. How many miles do you get when the fuel light turns orange? If you get above 260miles then your good.

On my 2002 M3 i managed 19.2-19.7mpg all the time. The only mods i had was drop in filter, lowered and CCWHEEL Forged 19in wheels.

Good luck.

Probably not getting 260 miles on an entire tank (not sure about the light)... I've already used two tanks of gas in the past 9 days since buying the car, and I've only driven about 420 miles.

What is this sport mode you speak of? I assume you're referencing an automatic? I don't see any sport mode on the 6MT.

Originally Posted by RPM90

I was thinking a bit more, and I remember that there was an early issue with some 135i wastegate actuators. Mosty, I believe, they were rattling.
But, I would still check to see if perhaps you may have one of them stuck a bit open and fully closing as it should. That could explain a greater sense of "lag" as a not fully closed wastegate would simply be loosing boost before enough pressure builds to overcome the small leak.
You would feel that as a greater lag.

I asked about the rev matching, because you are throttle blipping to do this, and any time you blip that throttle you're using fuel. In the rev match scenario you're using some fuel to go no where really, just to spin the engine up to match the rpm for the lower gear.

The heel/toe is a bit odd on this car, I agree. My 325i had a better setup.
The plane of the throttle and the brake seem a bit off, and it "feels" like the brake is a bit too far to the left.
In a heel/toe, you're still rev matching, but in a more controlled way as you control the throttle in a steadier fashion to balance the braking, gear change, and turn.
It just takes a bit more time due to how the pedals are placed, but it starts to feel ok when you get more used to it.
I do wish the pedals had a more natural placement though, as it would cause me to heel/toe more often.

Yep, I've heard about that wastegate issue. I have a 11/07 build and I believe most N54s after 9/07 used the new ones but some apparently have the old ones till January 17th, 2008. I would have to ask the dealer and they might not be willing to do work to find out unless the problem is related (or they think it is). A bit of a catch-22...

Would anyone be willing to let me drive their 135i in the DC metro area, so I can compare my 135i to it and make sure I'm not just crazy?

Originally Posted by CrazyIvan

I say, screw the mileage. It all depends on your driving style, road conditions, tire inflation, etc. But what do you expect from 300hp car? If you want great mileage, buy a Prius or diesel. I get low 20's in town mix. Doesnt bother me a bit, but it sure is fun to dust all kinds of people

I would say screw the mileage, too, if I had an E60 M5... but 300hp isn't that much these days, and from what others are saying, my mileage is on the low side...