How accurate is range?

[DEVO]

For those that have the trip computer option, one of the option is estimated range left. It uses the amount of fuel in the tank as one of the variables in determining the range, how accurate is this range? I managed to put in 13.6 U.S. gallons of gas and it said I had 22 miles left. I thought the tank was 13.2?

Thanks

[Mister]

Hmmm. That's interesting. I sometimes look at the range just out of curiousity when my fuel is getting low low, but I'd never rely on it being 100% accurate. Yikes! Most the time I just leave it at the temperature setting. I can understand how that works!

[Dec]

(my trip computers biult into the sat nav don't know if that makes any difference but...)

I dont know exactly but i think when it gets down to the lower numbers (under 20) it seems to drop quickly (as in quicker then 1 every mile) but ive driven it (by accident) past 0 and had it displaying --- for about 2miles when i went a bit too low (and i still think there weres a few litters left to fill)

The bottom line for me is it not good for the car to run near empty so i try not 2 and only use the range as a gide. its good enough as a rough estimate.

Dec

[Neil the Hat]

Have accidently on two occaisions seen zero on my range, and luckily both times was able to make it to a petrol station before I totally ran out.

For me it was good to know that the car won't stop sundenly when the readout says zero.

However it isn't a practise I would recommend as the stress levels get a little high

[spjessop]

I got to five miles left on mine, and the engine kept stalling in hills.

I'd say mine was pretty accurate.

[jon vital]

I've driven a few times with it showing -- -- --

Maybe that wouldn't happen if there was some sort of proper low fuel warning on the car.
I've run out once before, luckily right next to a BP station!

[stephenjc]

Quote: Originally Posted by DEVO

For those that have the trip computer option, one of the option is estimated range left. It uses the amount of fuel in the tank as one of the variables in determining the range, how accurate is this range? I managed to put in 13.6 U.S. gallons of gas and it said I had 22 miles left. I thought the tank was 13.2?

Thanks

Just a guess but I presume the OBC has an upper limit in calculating the number of gallons you have in the tank. Now whether that is 13.2 or more I would have no idea. Most cars I have owned i have been able to get more than the stated capacity in the tank. I think this is due to overfilling to a point where the gas level is to the top of the tak and then up the lines that lead to your gas cap. I think you are not supposed to do this.

The range I think is calculated based on the estimated gallons in your tank and the manner in which you drive - the obc's record of what kind of gas mileage you generally get. When you fill up it is obviously a rough estimate because certainly the OBC is not able to know if you will be doing a lot of city or highway driving on that tank. I have actually watched the range numbers go up as I drive when i am doing a lot of highway driving. I would presume that as you get closer to empty the range estimates become closer to accurate. A good test for your question would be to note what the range says after you fill up and zero out your trip odometer. Then when empty see how many actual miles you got and compare to what your OBC originally said. Again the range estimates do change as you drive depending on city/highway mileage.

I have and have had other cars with a range feature and zero has never meant that you are completely out of gas. I can get at least 20 miles beyond zero. Whether this is by design or just a limitation of what any OBC can do i don't know. I have never run out of gas on these cars so thankfully I don't know the upper limit of how far I can go beyond zero.

[DEVO]

Thanks, and yes I'm aware that the range changes depending on many variables. I guess the 13.6 that I got into the tank was surprising because I left the pump stop automatically. So I guess the line above the tank was filled as well.

Thanks for all the replies.

[termigni]

mine seems like it throws historical record also to calculate the range.

[OldRick]

Gasoline expands considerably when warmed. I expect that they state the capacity as the maximum amount that won't overflow.

[Eelke]

Wouldn't you say the volume increases as well, when your gasoline expands?
Also, if this were the case, you'd never know how much you can put into the tank without completely draining it first, and you should stop before the filling is automatically cut off.

[twouptons]

We put in 13.7 once with it reading 2 and have put in more than 13.6 two other times (22 and 16 on the OBC, IIRC).
It could also be miscalibrated pumps...

OTOH, I drove to my mother's house (75 miles) on some back roads (around 50mph) one pleasant Saturday and got there with the range reading higher than when I'd left

In general, it seems a pretty good reflection of how you have been driving recently, though in the short term (over a minute or so) it can have some really flaky reactions that seem kind of strange, like a range that increases after dashing madly away from a stoplight.

I'm not sure what sort of a "proper" low fuel warning we would need, though. In addition to the range, we have the little red light that comes on at around 2 gallons remaining...

-Eric

[cooper-minx]

My Mini manual says not to go lower than 50 miles/35km showing on the range left.
It says that going lower can cause damage!

[Yorkshire Lass]

Quote: Originally Posted by cooper-minx

My Mini manual says not to go lower than 50 miles/35km showing on the range left.
It says that going lower can cause damage!

Oops! I might be in trouble then as I didn't notice I needed petrol until I was on the motorway today.

The computer couldn't make up it's mind how far I could go though it started at 11 miles then quickly went down to 5 then back up to 11, down to 1 (scarey moment as I was still acouple of miles away from the junction! ).

Basically I think I should have taken the mini sales girls advise and filled up at a quarter full as that last quarter doesn't go very far!

[MINIRANDOLPH]

Mine seems pretty accurate give or take a few miles.