99 s80 45 mpg at 50 mph? is this right?

jimgrames62 · Post by **jimgrames62** » 26 Nov 2010, 22:29

I can't believe it! Is there something wrong with my s80 or is anyone else getting this? Ok yea it was a level 10 mile stretch of road with cruz on 50 and no a/c but 45 mpg??? Car has 136k mi. and yea she does run very smooth but is this normal? I just can't believe it? Were talk'in bout a 2 ton car here? Maybe it is worth keeping?

Post by **precopster** » 27 Nov 2010, 01:47

That's great but what does she get up a hill with A/C running, against a headwind, in warm weather and fully loaded? I think you'll find it all evens out to approximately 24-30 mpg on average for town use and 30-35mpg for highway use.

To perform a more accurate check totally fill it up with gas, reset the trip counter, run it until it's almost empty, then refill totally again. Count the fuel taken to refill versus the miles completed. This ratio is the MPG over a large sample time, not just a momentary glance at the trip meter over 10 miles.

Post by **mvsuzr** » 27 Nov 2010, 22:59

A few thoughts:
1) The road might not be as level as you think. Run the stretch both ways to get a better mileage figure.
2) Make sure you're using the avg mpg, not the instantaneous. And, reset it before you run your checks. My T6 averages about 20mpg, but I can get a satisfying 72mpg on a strong downhill, A/C and all. Don't ask about the uphill mileage!
3) Compare your average mpg with the calculated average as 'precopster' suggests. If you consistently show a higher average than you calculate, it may be time to start checking your sensors, could be something is starting to fail and it's fooling your computer. Likely this will result in a failure code pretty soon, though.

jimgrames62 · Post by **jimgrames62** » 28 Nov 2010, 05:55

sorry guys, i was just gloating about the fact that this big beast of a car can get this kind of mileage. theres nothing wrong with the car. any car can get this. just first set cruz at 50 then do a reset of your average mpg and see what she gets. i'm sure any smaller car out there will get better than a s80? i was just surprised.

Retired MVS Contributor · Post by **Retired MVS Contributor** » 28 Nov 2010, 06:25

That is an instantaneous reading, not true over-all mileage...The computer has several settings that you can use...For example, instantaneous, average, remaining fuel, etc...If you use instantaneous mileage, you will get misleading readings like that...I have seen readings in the 60's during deceleration, but it is an instantaneous, closed throttle reading...The computer takes a sample reading at a given time, ramps up the display, and by the time it is displayed it is already old hat while it is setting up for a new reading...The average reading is not helpful during trips because it is the average calculated over the life of the car from day one at the new car dealer and probably about 15 MPG for most of us...It includes highway use and driveway idling...If you get on a flat throughway and put it into cruise control you will get a very nearly constant reading and that is true mileage at that time...At 70 MPH on the Pennsylvania Turnpike my XC registers between 27 and 28 MPG but it is no where near that in street driving...

Jerry

jimgrames62 · Post by **jimgrames62** » 28 Nov 2010, 06:54

wasn't trying to get a average reading just making an observation to see what it would get at 50mph. sorry NOT instantaneous reading but this was a average reading. like I was saying this was only a 10 mile level stretch of road. got the car doin 50, set the cruz and did a reset of the average so as to zero it out. not a bog deal on this guys any car will get this if you set it up this way. i'm sure a s60 or s40 will do better? or any car?