MPG on your Z4 M?

[donoman]

Originally Posted by Pheonix

You might get 25.5 MPG if you are driving like a granny with mostly downhill roads.
Not sure how accurate it is but the MPG is 20.6 on my dash (for over 10k miles now).

I have been trying really hard to drive smooth all week, that's just about what I am averaging right now. My daily commute is pretty mixed. 8-9 miles to work on the freeway but a few miles here and there for local trips in the city.

[Pheonix]

My commute is 31 miles each way with 90% hwy and somewhat heavy traffic. I could probably get 22MPG if i slow down to 60-65 MPH. I figure it is not worth slowing down since the SPG is priceless

[dschultz]

25 mpg, door to door, @ 65 mph, 37 hwy miles, 1 mi surface roads.
Long term when I'm not trying to "hyper mile" is 20-21 mpg.

[zgood4u]

18-19 average. Traveling from Atl to Pitt got about 21, that's about as good as it's been for me, no complaints though.

[bdc]

Hey, seank, you may call it bs, but it's the truth. What motive would I have to lie. No it's not an M. 2007 3.0i, 6 speed. I don't drive like a granny. I'm actually pretty hard on acceleration. When on the highway I keep it around 70. If you want to do the math, since I bought the car I've put 10,114 miles on the car in 8 months. In that time I've made 32 fill ups for a total of 407.63 gallons (at a cost of $1,385). That works out to just under 25 mpg. That's an advantage of using a phone app to track these details.

[donoman]

Originally Posted by bdc

Hey, seank, you may call it bs, but it's the truth. What motive would I have to lie. No it's not an M. 2007 3.0i, 6 speed. I don't drive like a granny. I'm actually pretty hard on acceleration. When on the highway I keep it around 70. If you want to do the math, since I bought the car I've put 10,114 miles on the car in 8 months. In that time I've made 32 fill ups for a total of 407.63 gallons (at a cost of $1,385). That works out to just under 25 mpg. That's an advantage of using a phone app to track these details.

He called BS on you because he's running an M and probably didn't realize you're running the 3.0i. I can also do 25-27 MPG on my 2.5i; the M is just particularly hard to get good MPGs out of.

[seank]

Originally Posted by bdc

Hey, seank, you may call it bs, but it's the truth. What motive would I have to lie. No it's not an M. 2007 3.0i, 6 speed. I don't drive like a granny. I'm actually pretty hard on acceleration. When on the highway I keep it around 70. If you want to do the math, since I bought the car I've put 10,114 miles on the car in 8 months. In that time I've made 32 fill ups for a total of 407.63 gallons (at a cost of $1,385). That works out to just under 25 mpg. That's an advantage of using a phone app to track these details.

I thought it was an M since that is what the thread is about. I take it back and I'm sorry. If it was a M, I would call you a lier.

[Dalecan]

My road trip from Seattle to Vegas returned about 25.7 mpg. This was a mixture of freeway and back roads, with lots of spirited driving when possible. I was really impressed with that.

[Pheonix]

EPA Estimate MPG for the 3.0 Z4 is 18/21/28 (City/Combined/Hwy) vs. the 3.2 Z4M is 15/17/21. I would considered getting anywhere near these numbers are correct. For those whom get way over those numbers, you probably got a freak from the factory or you driving style and route matching hypermiling.
By the way, the Z4M subjected to Gas Guzzler Tax to the original purchasers

[bdc]

I didn't realize M's were more thirsty for gas.

[Vanne]

More horses = more fuel.. Pretty much
Not sure why you yanks actually care though, you guys have some of the cheapest fuel available to you. Now the poms on the other hand ...

; )

[strokeoluck]

Wow, you guys are impressive. I never, ever, look at the MPG info on the car. I sometimes look at the temperature and certainly the speedometer and RPMs but otherwise my eyes are either on the road, the radio or the person sitting next to me. Gas could go to $10/gallon and mileage down to 10 mpg and I still don't think I'd glance at the mileage figure. This car is a hoot to drive, so I just consider it my little vice, regardless of the cost.

[donoman]

Tracking MPGs is one of the best metrics to quickly judge the health of your car. It's not just about the price of gas.

With that being said, I did about 250 miles in the Z4MC today, most of it on the freeway, never exceeding 78mph (my speed alarm is set to remind me to slow down at 78), and got 23 MPG.

[nesrevival]

21 avg 50/50

[EenyBear]

Yeah - mileage as an indicator of car health.

When I first got my Z4MC I thought I was using more gas than I should be... even with spirited driving in sport mode. It was way way way below the EPA estimate and suggested that attention was required somewhere. The car felt OK otherwise but it sure was thirsty.

Ironically, if I had been getting close to the EPA estimate I would have done nothing (as so many of us do).... and would have missed the opportunity to learn and improve my M's efficiency.

So... I scoured these forums for info. Shipkiller tipped me to considering the O2 sensors. I ran a simple iPhone-based diagnostic with an app called "Rev" and sure enough one sensor seemed way outside the norm and another was even farther out of sync. I don't know enough to analyse the values provided by the diagnostic, but two were similar and two others were markedly different. To a guy like me, all that meant was something was wrong with two or maybe all of the stock sensors... similar to Shipkillers experience... so I decided to replace them.

Another forum member suggested some O2 sensors with a record of high QC in manufacture and yet another offered to procure them for me at a reasonable price and ship them to me. If it's important to anyone, the conversation can be found in these forums. The price was better than eBay and I was told they would be "matched". Not really knowing much about what that meant or even if it was meaningfully true, I trusted and went on faith.

Then, because he took it as a personal challenge, my indie mechanic went over the whole car looking for loose hoses, and anything else even remotely connected to the fuel/air delivery system. He has seen a lot of Z4Ms and was aware that some significant differences could be found between cars due to age, variation in OEM component selection, component failure or simple substandard performance, driving style, maintenance schedules, etc. Normal stuff we can all recognize as having an effect over time.

Besides the O2 sensors, he tweaked the throttle sensor and tweaked the tune a little, and gave me some spanky hi-tech spark plugs. And yes, even an air/vacuum hose that looked new, tight and leak-free was clearly identified with a poor seal and was adjusted. Again, I went on trust... and I wasn't being gouged... and the data supported the diagnosis.... so I agreed to the work. Much of it was no additional cost beyond the labour to install the O2 sensors. Paid for itself in no time.

City driving (brutal stop and go) mileage climbed dramatically to the still rather unimpressive heights of 16-17 mpg US but the highway mileage skyrocketed to the mid 20's even in sport mode with RPMs kept well above 4500 (often very well above). If, when I get up to a comfortable but still smile-inducing cruising speed and then take it to 6th gear... I can get 26+ mpg US all day long. For back-road jollies, I rarely get above 4th gear and the mileage drops to the still satisfactory low 20's. It's just a number but if it changes, I'll notice and investigate.

No big deal. Don't call BS on an M that gets above-average mileage. It was relatively easy to accomplish in my case without driving like my granny. I'm no expert. I just did some research, asked for some help, and did what was suggested by people I trust.

In fact, if I drive like a granny at 60-70mph in 6th I can easily coax the car down to 7.9 litres/100 km ..... equivalent to 29.77mpg US. But that's not how I choose to drive my M. It's not why I bought the car. But it can be done. On the other hand, if I never take it out of second gear with sport mode on it will cost me more in fuel... which dampens my enjoyment after a while. But for short periods, its a gas (pun intended).

So rather than calling BS, think about what I and several others here have done and then accomplish it yourself if you want to. It's not magic.

For me, it's just a new baseline number to keep track of vehicle health without getting too worked up about it.

By the way, I got rather tired of the OEM tires and recently put on some properly inflated Michelin Pilot Sport A/S 3s. The specs suggest great wet/dry performance, short braking distance, and long life. That's the holy grail of daily driver tires in my book. Lower rotating weight? Yes. Improved mileage? Maybe, in theory, due to an extra pound of pressure all round ad the lower weight. More smiles per gallon? Definitely.

I hope this is helpful.
Cheers,

[bdc]

Nice response, Eenybear. Since I got my car last August, and phone apps are sooo easy to use, it's now a habit to log every fill up.

[donoman]

Eenybear, great response. It should be stated that California gas is different than gas in other states so members should expect 10-15% less MPG than their non-CA counterparts. This is my understanding from reading on the internets, which is always correct.

[EenyBear]

Hmmm... we don't see much ethanol fuel where I live so I neglected to mention the E85 fuel or other ethanol blends as a factor - but, you're correct, of course.

The debate over ethanol substitutes/blends has many pros and cons. A quick search of the old webbernet will confirm that. Whether or not it is more efficient to produce than a pure petroleum-based fuel is open to challenge. But the demand for fuel and the favourable economics for corn (and other cellulose) producers generally indicate that ethanol is here to stay.

Even some green advocates will acknowledge efficiency reductions of up to 25% (i.e. 18mpg instead of 24mpg) but most suggest as little as 3-5%. Again, it depends on the blend and who is doing the reporting. 10% ethanol? 15% ethanol? More? Corn lobby? Alternative fuel activists? Petroleum salesmen? Who knows..... Use critical thinking skills to draw your own conclusions.

For auto enthusiasts like us, there are a few things to remember about ethanol blends beyond the efficiency debate - important, because in some areas it's the only fuel available.

Ethanol is hydrophilic. It absorbs water. It has a shorter shelf life than 'pure' gasoline and can get "gummy" faster which is hard on filters.

The good news is that because it's hydrophilic, the water passes through the system instead of accumulating. The cautionary note is that tanks should be kept full (especially when stored) to prevent over-absorption of moisture. This is especially important for seasonal engine use like for boats, motorcycles, and garages queen Z4Ms. For year-round DDs it's not really an issue.

Ethanol is corrosive. Engine parts do not last as long with its use. Total effect and risk.... I don't know. I frequent a motorcycle forum where there is ongoing heated discussion about ethanol fuel's effect on seals and other bits. Bikers don't like it - even when mileage is the last thing on their minds.

For us here, it's important because we tend to keep our cars longer or at least take good care of them while they are in our care.

How we respond to all these factors - in the context of our automobile health - is more important than concerns about the inevitable loss in power and declining mileage.

How we respond to these factors - in the context of a diverted food supply... and the carbon footprint of production compared to any reduction in carbon footprint from use - is a matter for another forum, I think.

On a related topic, I have found that Chevron 91 (no ethanol) is better for both my R1200S motorcycle and my Z4MC than Chevron 94. Interesting. The 94 seems to reduce responsiveness (especially on the motorcycle) and makes both engines a bit "whiney". My Z4MC gas cap says to use fuel with ROZ/RON of 95-98 which is equivalent to the US/Canadian octane labels of 91-95 (typically R+M/2). So you would think the 94 Chevron would work well and perhaps better than 91. Not necessarily the case for me. YMMV

Fuel is a very complicated issue.

The very short answer is that the type of fuel available (and altitude, and ambient temperature, etc.) is a contributing factor to mileage.

So..... what can we do? Simple. Track your mileage for 3-4 fill-ups. Also use the car computer to reset and check reported mileage during periods where the driving conditions remain the same. I mean, if you are about to hit the highway for a few hours, reset the mileage indicator and check the number and make a note. If you are going to be driving around town for a while, do the same.

If those numbers change... you have an indication that something has happened. Are you using different fuel? Are you enjoying a little spirited driving off the line? Or..... is something starting to fail?

Fuel consumption is one "canary in the coal mine" that we can observe to monitor the overall condition of the car. One person's 18mpg compared to another person's 21mpg is meaningless in the grand scheme of things. But if your 21mpg drops to 18mpg within a few tankfuls it becomes very important indeed. And, if you experience 10-12mpg like I did for a while... it's time to take action (described above).

Again, I hope this is helpful.

[fiberguy]

In almost 5 years of ownership, I've driven 31113 miles and used 1433.5 gallons of gasoline. That computes to 21.7 mpg. It's 70% interstate (65 mph), 20% stop and go and 10% interstate stop and roll.

The absolute best I've ever been able to do was 28.5 mpg. That was 65 - 70 mph with cruise control on a 200 mile interstate run (top down) with rolling hill terrain, just me in the car and one overnight bag. I probably hit the brakes twice on the trip and was on cruise 95%. I also inflated the tires to max pressure.

No data on pure city driving.

Once upon a time I owned a 2.5i that averaged 27.2 mpg over 33,000 miles of the same driving. The "M Fun Factor" penalty is 6 mpg. At almost 63, I consider it money very well spent!

[funkle]

Last couple weeks my Z4M has only been used for quick jaunts through the city. If I drive to my gym, I'll go through Potrero Hill - this is where much of the Bullet car chase was filmed if you get the picture - very hilly, wide roads, no traffic, 4-way stops every block just a bunch of launches to 30mph. For this kind of drive, I just realized I'm getting a little over 9MPG. Much worse than the 16MPG I get when there is some highway and and less stop/go. I'm still only filling up once every 1 1/2 to 2 weeks, so I can live with it.

[kihtay]

Sorry old thread revival..

But I was kinda bummed- now that I have gone through a full tank of gas LOL
I was only getting about 16mpg. Most of that was freeway
In the 3.2L S52 M3 I was getting 25 with the same spirited driving. So I had higher hopes for this in regards to MPG

[XMetal]

16mpg on mostly freeway is definitely on the low side - you must have a super heavy foot I've been averaging 18mpg on mostly SoCal city driving. I couldn't get more than 23mpg on freeway cruising.