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Real world mpg
- Thread starter l1tech
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OP
Thread Starter
#82
When I did my trip to Tennessee i started with 93, first fill up avg was around 24 with doing 75-80. Switched to 87 on my first fill up because 93 was nearly a full dollar more and wanted to see how 87 compared. From there averaged about the same 24-25. Stuck with 87 the rest of the trip. I had to do a lot of driving where I was so I just continued with 87.
No, federal law allows a 5% speedometer error. I don't recall if it's plus or minus or total and I don't know if odometers are held to a specific range. A long time ago, manufacturers had the odometer read a bit high, so if Joe Consumer traded when it got to 60,000, it may only have 57,200.
The odometer in my ST is 2.3% low. The speedometer is as dead-on as I could ever expect (< 1mph). That 15% error is the computer's guess about the MPG.
The odometer in my ST is 2.3% low. The speedometer is as dead-on as I could ever expect (< 1mph). That 15% error is the computer's guess about the MPG.
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The odometer reading would be directly related to the speedometer reading, that would be how it calculated the distance travelled. Circumference of tires along with number of revolutions. Looking online it appears that thw 275/45ZR21s are about 3.4% smaller than the thw 255/55R20s. If Ford did not revise this in the ST that would account for some of the difference. I would assume that the measurement of fuel used would be suspect. After that calculating a MPG is pretty simple.
OP
Thread Starter
#88
Thread Starter
#88
This is not correct. There are many mfgs that purposefully make the speedometer read faster than actual speed but the odometers are accurate. For example certain model BMW’S read 2 mph faster than actual speed but the odometers are accurate. I think they do this to avoid complaints about speeding tickets.
I don't think I've ever had a vehicle where the speedometer and odometer had the same error. My ST's speedometer is as accurate as could be expected, but the odometer is 2.3% low. I don't recall if I checked the Limited. The Escape needed 1.8% added to the odometer reading to get accurate distance covered. The Mustang is similar. Both speedometers are very close. My Ram was WAY off with 285/70x17s from 245/70x17s.
Straight and level, with good satellite coverage, should give you a fairly accurate speed. Outside of those conditions, gps information would be suspect in my experience. For measuring distances on highways we use a meter reader connected to the vehicle and is calibrated to suit the individual vehicle performance against a known (physically measured) highway section. Then s=d/t.
Accurate to 10' is great for geochaching and finding you car after hiking, but not accurate at all for calculating the change in distance over a few seconds (I would think that your Garmin would sample more frequently than a few times a minute). At 60 mph your vehicle should move 88' per second and I would say if the GPS was out by 10' one direction for the first reading and then out by 10' the other direction for the second reading the total error could be 20' for what should be an 88' distance. That would be the extreme and likely it would average out, but the individual readings could be off by a large amount. I find my GPS to be close too, but it varies in readings as the vehicle maintains a constant speed by the spedometer. I have not noticed major discrepancies with my spedometer, that is why I am curious on this topic.
My mileage as calculated by the vehicle itself is usually between 23 and 25.
Long highway trips (VA to FL) we averaged 23.7 and was consistently around 80mph, summertime, and a rather full load of crap, 2 people and 2 little white fluffy girl dogs.
In town, which is a decent average mph of around 35-40mph (so not stop and go city driving), we get 23 every single time we fill up. We obviously drive very consistently and the same patterns.
We use 93 octane and drive normally, not crazy and not super slow either.
I have gotten 25.5 driving across Alligator Alley from Naples to Lauderdale in the "winter" and keeping it at the speed limit of 70 and actually trying to get the best mpg I could. That was literally all highway driving starting from the highway and ending on the highway.
2020 with 19,2xx miles on it and it is 2 years and 2 months old, bone stock.
Long highway trips (VA to FL) we averaged 23.7 and was consistently around 80mph, summertime, and a rather full load of crap, 2 people and 2 little white fluffy girl dogs.
In town, which is a decent average mph of around 35-40mph (so not stop and go city driving), we get 23 every single time we fill up. We obviously drive very consistently and the same patterns.
We use 93 octane and drive normally, not crazy and not super slow either.
I have gotten 25.5 driving across Alligator Alley from Naples to Lauderdale in the "winter" and keeping it at the speed limit of 70 and actually trying to get the best mpg I could. That was literally all highway driving starting from the highway and ending on the highway.
2020 with 19,2xx miles on it and it is 2 years and 2 months old, bone stock.
, guess mine just gets shittier fuel economy. Not going to sell it because of that, for now. I get rid of perfectly good cars all the time when my wife gets the itch for that new car smell.
