quick question

I own a 2002 S80 turbo. I wondered how accurate the computer is in
determining gas mileage. When my highway speeds average between 60 and 65,
my car's computer computes my gas consumption between 31 and 36 miles per
gallon depending on the terrain. It seems high to me. With gas prices
closing in on $2 per gallon, it is something I wonder about.

 

closing in on $2 per gallon, it is something I wonder about.

Hmm, I dream of $2 a gallon! I'm just happy that my volvo is now on LPG
and I can fill up in the UK for ~ $2.50 and that's phenominally cheap.

If you want to talk petrol prices then lets start the ball rolling at ~
$6.63 for an imperial gallon.

Your turn!

David.

 

My '87 Saab 9000 regularly gave 35 mpg at highway speeds. My son-in-law has
a later Saab 9000, and he gets the same mileage. Both had (have) 5-speed
manual transmissions. Automatic transmissions don't give as good gas
mileage. My 2000 S40, which is smaller, doesn't so as well, but it has an
auto tran

To check, you need to calibrate your odometer by driving a known distance,
and track the amount of gas you use as well as the mileage. Normally, the
computer is accurate.

 

Hi, P.S. - - -

You can double check the computer quite easily and accurately. I've
done it on both of our Volvo's (98 V70XC & 02 S60AWD). In both cases it
may be luck, but the reported numbers are right on the money.

1. Check the accuracy of the odometer. If you have any "official"
measured miles on nearby Interstate Routes, use them. Those same routes
have a mileage marker each and every mile, generally reporting miles
from the western border on east-west routes, and from the southern
border on north-south routes.

2. This done, calculate mpg based on gas required to top off the tank
from fillup to fillup, divided by miles covered during the interval.
Compare results with what the trip computer is reporting. Since the
required inputs are the same, verifying the one mpg range gives
assurance that all functions are verified.

No rocket science here, just the numbers. On a recent trip from Reno to
Elko, NV, we got exactly 31.0 mpg for the 300 miles trip. Fairly level
road, all at about 5,000' across the High Desert. Average speed
reported by the computer was just under 75, as that's the posted limit
and I generally drive at five over. Most of us have gotten similar
figures under similar inputs. There is one caveat, of course, and
that's the "Miles to Empty" number, which changes as mpg numbers vary.
This number is derived based on the average mpg over the preceding 12(?)
miles (or is it 6?). You can drive around town for a few days after a
fill up and see a number - then watch that number increase significantly
as you hit the highway.

As to mileage vs cost of gas - once again we see that our fellow
Americans have only one real concern: "Is it available?" Today's paper
reports SUV sales for the past month are up by 18%(!!) from the previous
month, while passenger car sales are down by a small %. For all the
concern for these dubious economic times, it's clear that too many folks
have altogether too much money - and no heart for conservation.

bob noble
Reno, NV, USA

 

I checked the accuracy of the reported MPG on my 2000 S80 T-6 and it was
always within one mpg of the manually calculated figure. I'm not even sure
which is the more accurate figure because the pumps have a certain allowable
error. The computer knows how many milliseconds each fuel injector pulses
for and the flow rate so it should be quite accurate. The highest mpg I've
ever achieved over a tank of fuel starting and ending at the same elevation
was 29.6 mpg. My speed varied between 55 mph and 70 mph. Mostly about 60-65.

Spanky