Login






BMW Garage  BMW Meets  Register  Search  Today's Posts  Mark Forums Read 

BMW 3Series (E90 E92) Forum
>
Averaged 42 mpgis this even possible?


10162009, 09:03 AM  #23 
Private
1
Rep 56
Posts 
What's the topography of that route? Is it constant elevation, downhill, how steep are the hills?
65 miles is not far. If a there is a significant downhill grade during that route your final average will reflect the benefit from the downhill stretch. If there are no appreciable uphill segments then I could believe that reported average. For a fair test you could have immediately turned around and driven back the reverse route...that would negate the benefit from changes in elevation and to some extent tail wind. 
Appreciate
0

10162009, 11:12 AM  #24 
just another bmw douche bag
110
Rep 3,637
Posts 
as much as I like to see my mileage meter sweep up into the 50mpg range, I realized you need to do the math at each fill up to calculate the true mileage. All the variables eventually average themselves out by the time you empty the tank.

Appreciate
0

10162009, 11:52 AM  #26  
Captain
22
Rep 756
Posts 
Quote:
Relying solely on the display is like predicting the weather using the outside temp gauge. 

Appreciate
0

10162009, 12:21 PM  #27  
Lieutenant
16
Rep 564
Posts
Drives: 2006 330xi 6MT
Join Date: Aug 2009
Location: Santa Clara, CA

Quote:


Appreciate
0

10162009, 02:12 PM  #28 
Lieutenant
16
Rep 564
Posts
Drives: 2006 330xi 6MT
Join Date: Aug 2009
Location: Santa Clara, CA

Out of curiosity, do you have an estimate on how much you save per year with all those calculations?

Appreciate
0

10162009, 02:20 PM  #29 
Smiling politely
116
Rep 7,934
Posts 
^^ Takashi  I do the same, albeit for informational kicks only, not trying to save $$. My car is a DD, so I generally always go to the same Shell gas station near where I work, even the same pump. Looking back on the data, the best tank I've had is 27.9 mpg actual (computer reported 28.0 for that tank), back in June 2007. Basically all highway for that tank, but driving through the Shenandoahs, so quite hilly.
I discussed this in another thread, but the computer is inaccurate. In 144 tanks of gas, it's never gotten the mileage exactly right. In fact, it has always reported too high. On average, it reports about 0.4 to 0.5 mpg too high, but it has been off by 1.0 mpg or more several times. Also, the computer rounds calculations in l/100 km, then converts to mpg, so you see strange rounding issues when you consolidate the data. Try sorting your "computer mpg" column on your spreadsheet and see how the numbers increase by 0.2 or 0.3 consistently, and the computer never reports the inbetween numbers. Also, the gaps in reporting intervals grow as you get to higher mpg numbers, since it's rounding at vol/dist and then converting to dist/vol. It is inaccurate over and above that rounding error, though. Anyway, this is uninteresting to most, but I thought maybe you, as a fellow gas tracker, might be interested.
__________________
330i  Black Sapphire  Beige + Burl  Sport  Premium  Cold  Nav  CA  Sat prep 
Appreciate
0

10162009, 11:27 PM  #31 
Drive till Infinity
21
Rep 118
Posts 
So I guess I DID not average 42mpg. I probably should have stated where I got this reading anywaymy GPS system.
As for where I was travelling, it was on the LIE (I495) traveling east bound from Jamaica to exit 62that is, if anyone is familiar with that area. As for the terrain, I'm not sure if the whole way is mostly downhill, or uphill or even just straight. I guess I'll be keeping an eye on it next time I travel. It was nice to think that I had 42 though =(
__________________
Drive till Infinity  '07 Jet Back 328i  SportLESS ._. 

Appreciate
0

Bookmarks 
Tags 
m mode, mpg, steptronic 
Thread Tools  Search this Thread 

