MPG meter accuracy?

[DBFIU]

How accurate is the computer at measuring mpg, i am getting like 28-29 mpg cruising at about 68 mph. Could this possibly be the case? if so it gets better mileage than my civic SI did.

[akak1997]

yes, it is possible. My trip from LA to Las Vegas last year get that kinda mileage when I'm cruising at ~70mph. I got there in less than 1 tank, and still have enough for me to drive around LV for a few days. When I fill up right before I leave LV back to LA I put in ~11 gallon.

[Taki]

I'm fairly certain the MPG meter uses the same "optimistic" speed of travel as the speedometer (the average speed function certainly does), so it probably reads about 5% high. Adjust your expectations accordingly.

[Tom K.]

It's pretty simple to check. Just find your odometer error by checking it against milepost signs on an interstate. Then reset the mpg readout each time you fill up with gas. Calculate your true mpg (corrected miles traveled divided by gallons used) against the computer readout over a few tanks and you'll know the error. Incidentally you can check your speedometer by comparing it to the computer (or the Navi system or any GPS if you have one) while doing a reset.

Over 22,000 miles, my speedomter is within 1% accurate, my odometer is 1.5% pessimistic, and my mpg readout is accurate within 1%. Like they say, your mileage may vary...

Tom

[ESC OFF]

If you are getting 28 - 29 mpg you are simply not driving fast enough.......



I've had similar readings, after 3,000 miles mine has been within 1-2%. It seems at speeds between 65-70 the efficiency is better than at 55 .

[MadMan77]

The best I have got is 28.2 MPG going ~80 MPH driving north on I-95 from Georgia to Virginia. You estimates are feasible there as long as there isn't too much in the way of traffic or passing situations.

[voerman]

If the 128 gauge is like the one in my E90, it is off by a lot on idle. The E90 read infinite miles per gallon when idling, the reality is 0 MPG. Bad engineering?

Lou

[DBFIU]

it says i get 33 mpg cruising at 65.

[jkp1187]

Originally Posted by DBFIU

it says i get 33 mpg cruising at 65.

Believable. I got 29 MPG average on a trip from South Carolina to Pennsylvania, and around the same on a trip through West Virginia and Ohio.

[Lucky1]

Has anyone been able to verify the accuracy using a GPS enabled device? I remember reading a post where people used those to prove the speedometer was accurate.

I filled up at a gas station along the highway, hit said highway and registered between 34-35mpg in my 128i after an hour trip or so traveling between 110-120km/hr. I've never registered that high before (of course never done pure highway driving before) but like someone said this would make the car more efficient on the highway than some older 4 bangers.

[BrokenVert]

Ok now why have none of you commented on my threads? I routinely get 30-35 MPG at slightly north of 70 and if I really try I can get my car north of 40 MPG...according to the car.

When I drive back up to Syracuse ill do a real check. The last time I did the ~ 250 mile trip on just over a half a tank of gas. Rough estimate is 31 MPG for the trip the car told me that I got 32.8 MPG, and thats slightly uphill the whole way.

The car actually becomes very frugal after 25K miles. I guess it takes that long for the car to fully break in? Its not unheard of on BMWs.

[DBFIU]

Originally Posted by BrokenVert

Ok now why have none of you commented on my threads? I routinely get 30-35 MPG at slightly north of 70 and if I really try I can get my car north of 40 MPG...according to the car.

When I drive back up to Syracuse ill do a real check. The last time I did the ~ 250 mile trip on just over a half a tank of gas. Rough estimate is 31 MPG for the trip the car told me that I got 32.8 MPG, and thats slightly uphill the whole way.

The car actually becomes very frugal after 25K miles. I guess it takes that long for the car to fully break in? Its not unheard of on BMWs.

Cool

[escobar929]

im averaging 23-26mpg mixed hwy and street

[jibaholic101]

Originally Posted by escobar929

im averaging 23-26mpg mixed hwy and street

wha?!?!?!

thats crazy, i am mixed between highway and street and i only get 18

[escobar929]

Originally Posted by jibaholic101

wha?!?!?!

thats crazy, i am mixed between highway and street and i only get 18

lol, i just got done thru the break in period last week so lets see if my good gas milage lasts

[Nicky G]

The thing that makes by far and away the biggest difference in my gas milage?

Pretty DUH, but whether or not I'm going up-hill or down-hill.

However, if you are taking a reading on a trip that has you mostly going either up or down, it's going to be a lot different than the way home!

[mechanicalmagic]

The biggest killer for my gas mileage is waiting at the friggin lights to get to the gas station. I was at 32mpg, and it went to 28, just waiting at the lights. YES, I checked it against the odometer, after fillup. NO, I have not checked the ODO against a GPS.
Mine is very close for highway trips, often within 0.4 mpg. City driving can be way off, at 2 mpg to the optimistic.
Yes, I'm a bit anal about recording fuel and mileage. Have a book in all my vehicles, record every cost.

[DBFIU]

I noticed my gas mileage go down drastically in the cold weather.

Used to be 32 mpg in 75 degree weather, now its 27 mpg in 45 degree weather.

Same speed, same weight etc...

[MadMan77]

Originally Posted by DBFIU

I noticed my gas mileage go down drastically in the cold weather.

Used to be 32 mpg in 75 degree weather, now its 27 mpg in 45 degree weather.

Same speed, same weight etc...

Say hello to my little friend: Winter blend gasoline...

[DBFIU]

Originally Posted by MadMan77

Say hello to my little friend: Winter blend gasoline...

Care to elaborate?

WTF IS WINTER BLEND...

[MadMan77]

Originally Posted by DBFIU

Care to elaborate?

WTF IS WINTER BLEND...

To sum it all up quickly is to say that "winter blend" gasoline is blended with more volatile but less energy dense ingredients such as anti-gel agents to help with freezing problems. This especially affects ethanol blended gasoline (e10, e85) since ethanol attracts and absorbs water and therefore is more prone to thickening or freezing in your tank in extreme conditions.

A quick search on Google will elaborate a bit more than this.

[DBFIU]

But I live in south florida, why would they use antifreeze agents in my gas? It doesnt get below 45F here.