Gas Mileage Accuracy
11-22-2009, 03:05 PM
#1
Racer
Thread Starter
Gas Mileage Accuracy
I have been tracking my gas mileage with an iPhone app called Car Care. I also use the gas mileage function in my car's computer.
There is a significant difference between the mileage that they report with the car's number being roughly 10% less than that calculated by Car Care. I assume that the Car Care number which is a simple calculation of the odometer increase since the last fill-up divided by the gallons of gas pumped is more accurate.
Two questions:
There is a significant difference between the mileage that they report with the car's number being roughly 10% less than that calculated by Car Care. I assume that the Car Care number which is a simple calculation of the odometer increase since the last fill-up divided by the gallons of gas pumped is more accurate.
Two questions:
- How accurate is the gas mileage reported by the car's computer?
- Is your car's computed mileage higher or lower (and by how much) than that which you calculate by dividing miles driven by gallons pumped?
11-22-2009, 03:16 PM
#2
Nordschleife Master
Your calculated value gives you an accurate gas mileage average. The OBC number is an estimate based on current driving conditions. I imagine it is pessimistic.
11-23-2009, 02:33 PM
#4
Banned
Join Date: Oct 2009
Posts: 731
Likes: 0
Received 0 Likes
on
0 Posts
11-23-2009, 02:34 PM
#5
Burning Brakes
I have done the math regarding mpg and found the computer
to be very accurate.
Surprise, surprise, it sure is amazing how driving the car
more aggressively significantly increases the fuel consumption.
to be very accurate.
Surprise, surprise, it sure is amazing how driving the car
more aggressively significantly increases the fuel consumption.
11-23-2009, 05:38 PM
#6
Banned
Join Date: Oct 2009
Posts: 731
Likes: 0
Received 0 Likes
on
0 Posts
I tried driving it more aggressively, upshifting around 3000rpms and not using 6th in town, and the mileage was about the same as when I drive like I always drive a standard, i.e. shift as soon as possible without lugging it. Can't seem to get more than around 19 mpg in town no matter what I do. My 3.5L 4-door E-Class with an automatic always did 21-22.
11-23-2009, 06:05 PM
#7
Burning Brakes
I tried driving it more aggressively, upshifting around 3000rpms and not using 6th in town, and the mileage was about the same as when I drive like I always drive a standard, i.e. shift as soon as possible without lugging it. Can't seem to get more than around 19 mpg in town no matter what I do. My 3.5L 4-door E-Class with an automatic always did 21-22.
24-25 mpg on the highway is also pretty standard.
You might be able to get closer to 28-29 mpg on the highway
if you are traveling 55 mph in six gear for a long distance.
Trending Topics
11-23-2009, 07:00 PM
#9
Drifting
11-23-2009, 07:27 PM
#10
Burning Brakes
11-24-2009, 12:58 AM
#12
Most of my driving is in the city. Most of my driving is on the weekend for fun, hence quite spirited. Car's computer says I average 14.4 mpg. My own math based on the trip odometer and fuel pump intake also equals 14.4 mpg.
I think the car's computer is pretty damn accurate.
I think the car's computer is pretty damn accurate.
11-24-2009, 03:41 AM
#13
I have got 27mpg on average (that's since I got the car) in a dfi C2S running 97 Octane in the UK. Nearly 40mpg on the motorway doing a steady 70!! My journey to work on a mix of motorway and main road returns about 30mpg. Very different if I step on the gas though!!
What do they put in your American petrol? Testosterone?
What do they put in your American petrol? Testosterone?
11-24-2009, 03:56 AM
#14
Nordschleife Master
I have got 27mpg on average (that's since I got the car) in a dfi C2S running 97 Octane in the UK. Nearly 40mpg on the motorway doing a steady 70!! My journey to work on a mix of motorway and main road returns about 30mpg. Very different if I step on the gas though!!
What do they put in your American petrol? Testosterone?
What do they put in your American petrol? Testosterone?
11-24-2009, 04:31 AM
#15
From the Porsche Brochure:
Extra-Urban mpg for 911 C2S - 39.8mpg (and Porsche are known for low-balling their mpg figures)
From the same brochure: Combined 27.4 mpg - almost exactly what I'm getting.
Thanks for clearing up the USA/Imperial discrepancy. I'd forgotten about that, damned EU's got me thinking metric nowadays. Give 'em an inch and they'll take a kilometer.
Extra-Urban mpg for 911 C2S - 39.8mpg (and Porsche are known for low-balling their mpg figures)
From the same brochure: Combined 27.4 mpg - almost exactly what I'm getting.
Thanks for clearing up the USA/Imperial discrepancy. I'd forgotten about that, damned EU's got me thinking metric nowadays. Give 'em an inch and they'll take a kilometer.