Some Complain about the Fuel Mileage on the M....

[Shipkiller]

Originally Posted by mhughett

Are people like this that claim that they get 27mpg on the highway basing this on filling up a full tank of gas and dividing the gallons into the miles driven or are they doing it by pushing a button on the OBC that tells them what mileage they are getting after resetting the button? Don't believe the computer.

I find it difficult to believe that a car that can have an EPA highway rating of 22 (in 2008 after the numbers were made more realistic) and yet people are getting 27mpg doing 80mph. If so, consider yourself very lucky. Personally, I drive a 50/50 mix and have been averaging about 18.5 over the first 1,000 miles. In the same driving conditions, my Z4 3.0si was getting 23+ and would get 30 on a long trip of 100% highway. I'll be interested to see how my M does with 100% highway but I'm not expecting much above 22-24.

As I have stated in other posts, when I set the cruise at 65, I get 26-27MPG.

Of COURSE your MPG will go down when the RPM's go up. I find that anything over 3K RPM then your MPG starts to really suffer.

When we went to HC08 in my wife's Roadster, trunk PACKED... and driving 75 MPH, I would get 31MPG... That was a memorable trip.... It was the first time I saw a MC in the flesh (Caddyshk's) and fell in love...

On the circuit to/from work, about 12 miles of city and 13 miles of highway, depending on how I drive, I get anywhere from 16 to 22 MPG. It all depends on my foot. I find that I drive very easy in the morning but start to hoon it up on the way home from work....

I also have made some posts about the accuracy of the trip computer. Mine seems to be very accurate. But I always do the Miles/Gallon computation....

As inTgr8r has stated and I whole heartily agree, these engines get amazing fuel mileage..

As I am driving home tomorrow, I can't wait to get into my ///M on Friday for the drive to work. To be in a real car again.....

[r4gs]

after purchasing my car in houston, i made the six hour journey west to del rio, almost 95% highway, averaged 80mph and 24.2mpg. from watching the consumption meter, i'm guessing the optimal speed for the m's (perhaps for most cars for that matter) to be between 70 to 75mph.

[RBull]

Originally Posted by Tonybest

What?

Read it over.

[jrich4411]

I see consistently 20 -21.5 mpg in my ///Mr. If I happen to take a trip with about half the tank run on the interstate - and I will do 75 minimum on the interstate - I will see my mileage hit 24-25. I would expect that if I did an entire tank on the interstate I could get it up to 28 or better.
In the FWIW dept... my winter car is a 2007 Ford Expedition Eddie Bauer. In the summer time I get 15-16 mpg. This is driving the same roads, traffic etc that I now use my ///Mr for during the summer, so my ///Mr is an improvement. A couple years ago, I took the Expedition out to Ohio to pick up my daughter from college. On the way home, I filled it up in literally a mile from the interstate. I then went over 400 miles before getting off the interstate in Troy NY. My gas guage said I still had close to a quarter tank (I normally would get just under 400 miles on a whole tank). Well, I didn't believe the guage - it had to be wrong, so I filled up. I checked the numbers and I had got 20.5 mpg in my fully loaded SUV. Again, this was literally the entire trip on the highway with the cruise set at 74. BUT, I can see how our ///Ms could potentially get in the high 20s doing a whole trip on the highway, even at the speeds *cough* some of us drive

[Tonybest]

Originally Posted by RBull

Yeah, I'm happy with it too. Last tank before track got 30.5 CDN combined driving.

I keep reading the "30.5 CDN" and still don't know what CDN stands for.

If it stands for Canadian than is the numeral 30.5 not the same value in the US?

[007MCoupe]

Originally Posted by mhughett

Are people like this that claim that they get 27mpg on the highway basing this on filling up a full tank of gas and dividing the gallons into the miles driven or are they doing it by pushing a button on the OBC that tells them what mileage they are getting after resetting the button? Don't believe the computer.

I find it difficult to believe that a car that can have an EPA highway rating of 22 (in 2008 after the numbers were made more realistic) and yet people are getting 27mpg doing 80mph. If so, consider yourself very lucky. Personally, I drive a 50/50 mix and have been averaging about 18.5 over the first 1,000 miles. In the same driving conditions, my Z4 3.0si was getting 23+ and would get 30 on a long trip of 100% highway. I'll be interested to see how my M does with 100% highway but I'm not expecting much above 22-24.

yes actually, i did my own math on my last 'road trip' to plano. from my house to the dallas and around town and up to plano, my odo had me at 372 for one tank until i felt i needed to fill up. computer had me at 27.6 but 372/14.5 doesn't = 27.6, more like ~25.5 IIRC. back and forth to work i don't bother doing the math. if i had to guess it'd probably be 14-16 at best.

either way, it's good to me to get over 300 with this engine and only 14.5gallons.

[esqu1re]

Are the speeds you guys are quoting ACTUAL (gps verified) or the displayed speed on the speedometer? I think there's like a 3-4 percent difference in my car (speedometer shows faster than actually going).

[007MCoupe]

Originally Posted by esqu1re

Are the speeds you guys are quoting ACTUAL (gps verified) or the displayed speed on the speedometer? I think there's like a 3-4 percent difference in my car (speedometer shows faster than actually going).

mine are from the speedo...

[mhughett]

Originally Posted by 007MCoupe

yes actually, i did my own math on my last 'road trip' to plano. from my house to the dallas and around town and up to plano, my odo had me at 372 for one tank until i felt i needed to fill up. computer had me at 27.6 but 372/14.5 doesn't = 27.6, more like ~25.5 IIRC. back and forth to work i don't bother doing the math. if i had to guess it'd probably be 14-16 at best.

either way, it's good to me to get over 300 with this engine and only 14.5gallons.

"Felt the need to fill up"? The car only has a 14.4 gallon tank and you took 14.5? I'd say you stretched this out about as much as you can without running it dry. I feel the need to fill up when the light comes on, which for me is usually just over 200 miles for my normal day-to-day driving.

[RBull]

Originally Posted by Tonybest

I keep reading the "30.5 CDN" and still don't know what CDN stands for.

If it stands for Canadian than is the numeral 30.5 not the same value in the US?

Imperial rather than measured in US gallons.

[007MCoupe]

Originally Posted by mhughett

"Felt the need to fill up"? The car only has a 14.4 gallon tank and you took 14.5? I'd say you stretched this out about as much as you can without running it dry. I feel the need to fill up when the light comes on, which for me is usually just over 200 miles for my normal day-to-day driving.

well at that point, i'd only had the car a couple weeks and it was my first road trip in it, so i wanted to see what i could get out of it i pushed it, i admit. IDK 14.4 14.5, i thought the manual says 14.5. either way, the computer said i had 5 miles left

but yeah, normal day to day i just fill up at 1/4 tank/wne the light comes on.

[dekaliber]

WTF. Is there something intrinsically wrong with my car that's limiting my fuel economy? At the end of the day, I don't drive enough to really care whether I get 16 MPG or 26 MPG, but I'd like to know if there's something wrong with my engine.

Granted, I've only taken one extended trip on the highway, averaging probably around 80 in 6th gear. Combined with a bit of local driving before I needed to fill up, ended up just over 18 MPG. This is (odo after filling - odo after previous fill)/gas added until pump stopped. Locally, I've seen as low as 13 MPG with no highway driving to around 17-18 mixed.

My tires are properly inflated. Car is completely stock aside from OE strut brace and aero side skirts. I rarely take it above 6K RPM, usually shifting around 3.5 or 4K. Sport mode never engaged. Ambient temperature in the 80s. Gas is always Shell V-Power 93 octane. Last oil change done maybe 2 months. I weigh ~170 lbs. with clothes and there is rarely ever anything else in the car except for a laptop bag and carpet floormats. Windows up above 50 MPH, AC on if necessary.

Only thing I can think of is that the dealer might have overfilled my oil. I have to double check on my next drive, but there's probably an extra half quart in there that I fashioned a syringe to extract. During the PPI, they found that my oil was overfilled from the previous owner too. Is there anything else I should check?

[Shipkiller]

Originally Posted by dekaliber

WTF. Is there something intrinsically wrong with my car that's limiting my fuel economy? At the end of the day, I don't drive enough to really care whether I get 16 MPG or 26 MPG, but I'd like to know if there's something wrong with my engine.

Granted, I've only taken one extended trip on the highway, averaging probably around 80 in 6th gear. Combined with a bit of local driving before I needed to fill up, ended up just over 18 MPG. This is (odo after filling - odo after previous fill)/gas added until pump stopped. Locally, I've seen as low as 13 MPG with no highway driving to around 17-18 mixed.

My tires are properly inflated. Car is completely stock aside from OE strut brace and aero side skirts. I rarely take it above 6K RPM, usually shifting around 3.5 or 4K. Sport mode never engaged. Ambient temperature in the 80s. Gas is always Shell V-Power 93 octane. Last oil change done maybe 2 months. I weigh ~170 lbs. with clothes and there is rarely ever anything else in the car except for a laptop bag and carpet floormats. Windows up above 50 MPH, AC on if necessary.

Only thing I can think of is that the dealer might have overfilled my oil. I have to double check on my next drive, but there's probably an extra half quart in there that I fashioned a syringe to extract. During the PPI, they found that my oil was overfilled from the previous owner too. Is there anything else I should check?

Here is something to check.

Two years ago, my Roadster was suffering from MPG issues compared to most others I found on the boards.

The engine threw no codes and there where no drivability issues other than a 5-9 MPG loss.

With out a code it took some detective work.. Long story short, both of my upstream O2 sensors were weak but NOT throwing a code. The sensors were always showing the DME a lean condition, which means they were dumping fuel into the cylinders. Using my AutoEnginutiy Laptop scanner I was able to figure this out...

I replaced the sensors and the problem was fixed. The dealer probably won't touch that issue without a code....

Not saying this is your issue because MPG issues could be so many different things and have a lot if variables...

[mhughett]

Originally Posted by Shipkiller

Here is something to check.

Two years ago, my Roadster was suffering from MPG issues compared to most others I found on the boards.

The engine threw no codes and there where no drivability issues other than a 5-9 MPG loss.

With out a code it took some detective work.. Long story short, both of my upstream O2 sensors were weak but NOT throwing a code. The sensors were always showing the DME a lean condition, which means they were dumping fuel into the cylinders. Using my AutoEnginutiy Laptop scanner I was able to figure this out...

I replaced the sensors and the problem was fixed. The dealer probably won't touch that issue without a code....

Not saying this is your issue because MPG issues could be so many different things and have a lot if variables...

Those are some expensive parts to be replacing unless you have a pretty good idea that it was causing the problem. So what was your before and after mpg?

[wasupdu]

While I don't have an M, I do have a CLS63 AMG that gets about 15 mpg city/highway, Z4 about 28 mpg city/highway and about 40 mpg on my Yamaha R1. In other words, I figure that balances everything out. I'm getting just over 20 mpg average on the vehicles I drive...lol

[Shipkiller]

Before MPG was 23-25. After 30-32.

Remember, this was on the non-M Roadster..

I was able to monitor the O2 sensors in real time and discovered that the voltage range they were running at was 0 to .4V. They should be .2 to .9V with .45v as the center point for the cross count.

[aerobod]

Originally Posted by dekaliber

WTF. Is there something intrinsically wrong with my car that's limiting my fuel economy? At the end of the day, I don't drive enough to really care whether I get 16 MPG or 26 MPG, but I'd like to know if there's something wrong with my engine.

Granted, I've only taken one extended trip on the highway, averaging probably around 80 in 6th gear. Combined with a bit of local driving before I needed to fill up, ended up just over 18 MPG. This is (odo after filling - odo after previous fill)/gas added until pump stopped. Locally, I've seen as low as 13 MPG with no highway driving to around 17-18 mixed.

My tires are properly inflated. Car is completely stock aside from OE strut brace and aero side skirts. I rarely take it above 6K RPM, usually shifting around 3.5 or 4K. Sport mode never engaged. Ambient temperature in the 80s. Gas is always Shell V-Power 93 octane. Last oil change done maybe 2 months. I weigh ~170 lbs. with clothes and there is rarely ever anything else in the car except for a laptop bag and carpet floormats. Windows up above 50 MPH, AC on if necessary.

Only thing I can think of is that the dealer might have overfilled my oil. I have to double check on my next drive, but there's probably an extra half quart in there that I fashioned a syringe to extract. During the PPI, they found that my oil was overfilled from the previous owner too. Is there anything else I should check?

Overall doesn't sound out of line for an ///M consumption.

I would say that to get the BMW specified consumption, you have to drive with a light throttle and keep the revs between 2000 and 3000RPM. In Canada the highway consumption rating is 9.0l/100km (26.1 US mpg), the best I have ever managed is 8.9l/100km (26.4 US mpg) at a steady 110km/h (68mph), when measured by litres used at the pump. The urban rating is 14.5l/100km (16 US mpg), the normal I achieve is about 13.5l/100km (17.4 US mpg), the worst about 17l/100km (13.8 US mpg) when driving fairly aggressively.

[r4gs]

aerobod, ur figures sound about right. i just took a trip out to lake pecos to catch the sunset, and did a bit of mpg readings on the bc myself. seems like the car could do with a 7th gear for further improved fuel economy, especially at speeds in excess of 70mph. i'd revise the most fuel efficient cruising speed to be about 65mph, giving me on average about 28mpg. am on 93 octane so that may have a slight impact.

[aerobod]

Originally Posted by r4gs

aerobod, ur figures sound about right. i just took a trip out to lake pecos to catch the sunset, and did a bit of mpg readings on the bc myself. seems like the car could do with a 7th gear for further improved fuel economy, especially at speeds in excess of 70mph. i'd revise the most fuel efficient cruising speed to be about 65mph, giving me on average about 28mpg. am on 93 octane so that may have a slight impact.

Normally E10 (10% ethanol) 94 octane for mine, probably would get 3% better fuel economy with straight gasoline, if it was available in 94.

[Caddyshk]

The best tank I've averaged was 8.4L per 100km - worst 28L per 100km