Low MPG

[jackronner]

I seem to be getting poor MPG on my 2005 R1200RT, around 38mpg max at 75mph, when most posters say they get 48-50.  I've noticed that the real-time mpg feature on the computer display sometimes seems to freeze despite radically different engine demands and speeds.  I would think that this feature is independent of the fuel injection computer itself, and that any possible malfunction in the MPG feature would not affect the the fuel mixture itself, but could this freezing possibly indicate a problem in the injection computer?  I've not relied on the MPG computer, and have derived my mpg figures from distance traveled divided by the amount of fuel at the next fill-up.  However, I haven't checked the odometer's accuracy over a measured mile yet, and wondered if the same computer that calculates the mpg also calculates the miles traveled, and whether any malfunction would produce a false fuel economy calculation.  Also, would a bad odometer affect the injection computation?  Stock wheels, tires etc., using 91 octane gas and I'm not heavy on the throttle.  The bike runs smoothly, with no smell of excess gas at the exhaust.  The low mpg doesn't seem to have been affected when I added a Rebus slip-on exhaust.  I did notice that the oil filler port cover was quite loose, tho' no leakage noted.  Would it have caused a pressure differential that would have decreased fuel efficiency?  I had a dealer run a diagnostic which didn't show any issues, so I'm at a loss.  Any thoughts?

[guest4915]

Are you reading UK posters MPG?

38 US MPG equates to 45 UK MPG, which isn't brilliant, but quite possible. I wouldn't expect much better than low 50s UK unless you're trying really hard.

[David.]

The MPG display on the on-board computer displays "average consumption", not  "real-time".

[ds99]

average consumption?

how does it calculate this? from engine start?, over the last XX miles, over the last XX hours of riding? since filling the tank up? etc

[David.]

Using the "INFO" button on the LHS switch, select the "average consumption", press & hold down the button until the reading in display has reset.

From this point on, the "average consumption" will be calculated until the value is reset again.

I would guess that the calculated ave. MPG is a function of the distance covered in miles from the odometer, divided by the fuel used in gallons as metered by the FI system.

[Ganesh]

A suggestion is at the next refuelling, fill to max and reset all the trips and the fuel consumption on the computer make a note of the odometer as well. then cover a known distance and refuel and cross check. It would be very useful if you have a sat-nav or even the phone  with google maps which would give an accurate distance covered. This should tell you if there is a problem with the trips and odometer.

[T6pilot]

Ganesh is spot on. Fuel the bike to the max, reset trip computer, then do the math at next fuel stop, repeat a couple times and you will have a good guesstimate of your actual mileage
I do not trust bikes computer when it comes to mileage or miles to fuel up
In my case I figured the average miles per gallon fuel economy was 42(us gallons) so to keep it simple I figure 40MPG
Bike holds 6.6 gallons according to manual
Keeping it simple I round off to 6.5 gallons which at 40MPG gives me a range of 260 miles. I always resent my trip computer at each refuel so at 200 miles I start looking for a name brand station,

[jackronner]

I don't know if this reply will reach all responders to my original post, but thanks to all.  Particularly helpful was Pickaxe's reminder of the different UK measure.  Do you use (fittingly) Imperial gallons?  I do reset the trip odometer and do the math at fill-up, and I guess that the mpg estimates BMW puts out are a bit inflated.  Thanks to all,

[David.]

What are the BMW estimated MPG figures. This website might be of interest, Fuelly  http://www.fuelly.com/motorcycle/bmw/r1200rt/2005

38 (US) MPG or 45 (UK) MPG at 75 MPH isn't brilliant .

Have done a comparison between Tesco & BP fuel over the same 100 miles with the cruise control set at 70 MPH (Sat. Nav.).
Returned 59.9 MPG & 64.6 MPG respectively, using the physical full to full method.

Are there any issues with the quality of fuel in the US.

[gogs01]

.....
Have done a comparison between Tesco & BP fuel over the same 100 miles with the cruise control set at 70 MPH (Sat. Nav.).
Returned 59.9 MPG & 64.6 MPG respectively, using the physical full to full method .....

Not quite sure what you're saying here - 100 miles at 70mph on Tesco fuel, followed by the same 100 miles / 70 mph on BP fuel - or full to empty on Tesco fuel followed by full to empty on BP ?
The (almost) 8% difference is quite significant, but experimental error always exists with one-off, fairly short samples.
I've never noticed any significant difference between fuel brands or grades, but speed and environmental differences do certainly have an effect.
Both of your mpg figures are very good for a genuine 70 mph cruising speed - I thought I was doing well getting 54-56 mpg at 70-ish.

[David.]

Not quite sure what you're saying here.

The comparison was done by setting off from home with a full (to the brim) tank of Tesco fuel, doing 100 miles to Birch Services (M62),  then filling up with fuel, using the quantity of fuel put in to calculate the MPG.

Rode around Wales for a few days, then filled up with BP fuel at Birch Services for the return journey home. Got back home after the same 100 miles & filled up again, using the quantity of fuel added to work out the MPG.

In both cases, the speed was fixed at a Sat. Nav. 70 MPH using the cruise control.

[BoB21]

Somebody is going to say it so thought i would:- one is up hill the other down :))

[David.]

Saddleworth Moor is the highest point on the M62 Motorway. Home is one side, Birch Services are the other. Therefore, there is uphill & downhill in both directions.

[Ganesh]

Hi Jackronner, going back to your original question and the difference in US vs Imperial. Are the stats you are reading the US figures in your handbook / marketing material or the numbers we are using for the UK/European market such as 100km/ltr and mpg. However if it is 38mpg and US gallons, it still seems low as that in real money is about 45mpg as pointed out earlier. Mine has not dropped below 54mpg irrespective of how hard or loaded the bike is, except for one occasion on a motorway, somewhere not to be identified it was sustained 100mph plus over a distance of 50 plus miles it dropped to about 50mpg.

[exportman]

My average over almost 7000 miles is 47.34  miles to imperial gallon  but I do a lot of riding in traffic  and when I get out for a blast  I  tend to ride it quick quickly