Americas What is your petrol US gal mpg?

DezRoamer · Feb 14, 2024

Jiman01 said:
That‘s pretty good. Plus you’re at what 5000-6000ft above sea level?

6,000+
The only reason I like knowing accurate fuel consumption is for range. In some parts of the Southwestern US it can be important.
I know it's an IG forum, but this little 90 was brilliant off pavement.

Boston Boy · Feb 14, 2024

nuclearbeef said:
actual calculated mpg/ onboard computer
1) 13.8/ 16.6
2) 14.1/ 16.1
3) 13.4/ 15.7
4) 14.3/ 16.7
5) 13.1/ ??

new:
6) 14.2/ 16.5

Federal law allows factory speedometers to read 10% higher or lower than the actual speed (49 CFR 393.82. Since speedometer accuracy probably tracks with odometer accuracy, why would any auto maker not have their speedometers read high? A 10% overestimation of miles driven should translate to some very real savings in warrantee claims.

LC0013 · Feb 14, 2024

Boston Boy said:
Federal law allows factory speedometers to read 10% higher or lower than the actual speed (49 CFR 393.82. Since speedometer accuracy probably tracks with odometer accuracy, why would any auto maker not have their speedometers read high? A 10% overestimation of miles driven should translate to some very real savings in warrantee claims.

Heck of a good point there!

nuclearbeef · Feb 14, 2024

Boston Boy said:
Federal law allows factory speedometers to read 10% higher or lower than the actual speed (49 CFR 393.82. Since speedometer accuracy probably tracks with odometer accuracy, why would any auto maker not have their speedometers read high? A 10% overestimation of miles driven should translate to some very real savings in warrantee claims.

I believe the speedo is allowed to be 10% high and 0% low.

Mine reads 78 mph when traveling a true GPS verified 75 mph.
Assuming the odometer has the same error, when it reaches 30,000 miles; I will have actually travelled 28,846 miles.
It also would also skew my manual calculations of mpg since I use the odometer to determine miles travelled.
14 mpg would, in reality, be 13.46 mpg.

nuclearbeef · Feb 14, 2024

Next fillup:

actual calculated mpg/ onboard computer
1) 13.8/ 16.6
2) 14.1/ 16.1
3) 13.4/ 15.7
4) 14.3/ 16.7
5) 13.1/ ??
6) 14.2/ 16.5

7) 13.9/ 16.2

bradshow · Feb 14, 2024

I live in Charlotte, NC and drive on both highways and around the city and I average about 16.5-17.5mpg.

Krabby · Feb 14, 2024

bjsheeri said:
I live in Charlotte, NC and drive on both highways and around the city and I average about 16.5-17.5mpg.

Computer average, or one you manually calculate? There seems to be a significant discrepancy (see nuclearbeef's numbers).

pmatusov · Feb 14, 2024

nuclearbeef said:
Fuel mileage should improve as altitude increases.

Not with a turbo/supercharged engine.

pmatusov · Feb 14, 2024

Boston Boy said:
Federal law allows factory speedometers to read 10% higher or lower than the actual speed (49 CFR 393.82. Since speedometer accuracy probably tracks with odometer accuracy, why would any auto maker not have their speedometers read high? A 10% overestimation of miles driven should translate to some very real savings in warrantee claims.

Speedometer almost never track with odometer accuracy.

bradshow · Feb 14, 2024

Krabby said:
Computer average, or one you manually calculate? There seems to be a significant discrepancy (see nuclearbeef's numbers).

I’m referencing my computer average. I just checked and it’s 16.8

Rupert · Feb 14, 2024

OK, I'll bite. Porsche 911 is and is advertised in the operators manual as being 3 MPH above what is actual. Silly thing considering there isn't much difference between 147 MPH and 150 MPH.

Rupert only has 500 miles right now so I would say not a good comparison. Right now I am averaging about 15.5 on the trip computer, so it is most likely less than that if the math calc was done. I would say it will most likely be pretty settled after 2,500 miles and will post up again at that time. Honestly, if it got 10 MPG, I would still love it. I appreciate gas guzzlers, I wish everyone drove one. Guess what business I am in?

2wheelfish · Feb 14, 2024

Rupert said:
Guess what business I am in?

Texas tea, lol.

nuclearbeef · Feb 14, 2024

pmatusov said:
Not with a turbo/supercharged engine.

Why would this be?
Less drag due to reduced density.
You wouldn’t see the increase in engine efficiency due to reducing pumping losses as in a NA engine. But the turbo having to work harder should have only a slight reduction (if any) on overall engine efficiency.

pmatusov · Feb 14, 2024

nuclearbeef said:
Why would this be?
Less drag due to reduced density.
You wouldn’t see the increase in engine efficiency due to reducing pumping losses as in a NA engine. But the turbo having to work harder should have only a slight reduction (if any) on overall engine efficiency.

Only to reduced drag.
Non-forced induction engines tend to lose power simply because of less air density, and since/if they are running more or less stoichiometric air/fuel ratio, they use less of fuel.
Forced induction more or less masks that effect.

nuclearbeef · Feb 14, 2024

pmatusov said:
Only to reduced drag.
Non-forced induction engines tend to lose power simply because of less air density, and since/if they are running more or less stoichiometric air/fuel ratio, they use less of fuel.
Forced induction more or less masks that effect.

N/A engines will lose power at any given throttle setting and will make less max power.
But the air/fuel mixture will remain the same.
You will just need to use a more open throttle to make the same power.

pmatusov · Feb 15, 2024

nuclearbeef said:
N/A engines will lose power at any given throttle setting and will make less max power.
But the air/fuel mixture will remain the same.
You will just need to use a more open throttle to make the same power.

Going over the Coal Bank Pass on U.S.550 in the Range Rover Classic was a flat-out affair. I thought I'd burn a lot of fuel - but the gas mileage ended up a little better than at sea level.

YellowLab · Feb 15, 2024

Krabby said:
IMO 91 is much more premium than not. Having owned too many vehicles that required premium, I became a Sunoco fan. When they had 94 I ran it but they dropped that and max at 93.

Can't even find 93 in CA - its too evil for us....

YellowLab · Feb 15, 2024

Heater said:
So for the US, the verdict is what for Highway and other?

I think the MPG is calculated when the vehicle is parked

like all off roaders - its all down hill from there...

Ragman · Feb 29, 2024

My first tank hand calc was 16.5. Just ran a tank through primarily highway with punishing headwinds and was down to 11.6 which almost makes it a no go for long distance remote use since you have no idea what conditions you will face. I hope it is an anomoly.

Adding-US Gasoline version and under 1000 miles on odometer.

DaveB · Feb 29, 2024

I am using 12.3 L/100kms after 9,600 kms
Which is
19.12 US MPG after 5965 miles.
Mine is a diesel.
And i don't drive economically.

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Americas What is your petrol US gal mpg?

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