Anyone else notice MPG changes day to day?

[audtatious]

Say what?

So....Last Thrusday I drove one of my normal routes for meetings and decided to watch my mpg. At 75-80mph I was running around 23.xMPG. At 60-65 I was getting up to 28.7MPG. On Monday I did the same trip and at 80MPH I was around 21-23MPG and at 60-65 I maxed at 25.xMPG. Now, weather was relatively the same as both days were clear, relatively no wind, and I left at appx the same time each morning. Traffic was the same both days and I was watching the mileage at appx the same locations each time.

I have also noticed that on some days the G feels slower than others. I have not been able to map out what the differences are as some days seem humid and cool while others are dry and warm.

Anyone else notice this? I noticed MPG differences like the above in my Maxima but never really experienced where the vehicle felt faster on some days.

[zozoka1212]

Say what?

So....Last Thrusday I drove one of my normal routes for meetings and decided to watch my mpg. At 75-80mph I was running around 23.xMPG. At 60-65 I was getting up to 28.7MPG. On Monday I did the same trip and at 80MPH I was around 21-23MPG and at 60-65 I maxed at 25.xMPG. Now, weather was relatively the same as both days were clear, relatively no wind, and I left at appx the same time each morning. Traffic was the same both days and I was watching the mileage at appx the same locations each time.

I have also noticed that on some days the G feels slower than others. I have not been able to map out what the differences are as some days seem humid and cool while others are dry and warm.

Anyone else notice this? I noticed MPG differences like the above in my Maxima but never really experienced where the vehicle felt faster on some days.

One day you eat too much for breakfast and poor car has to take the extra weight. Extra weight = slower car and bad mpg.

Don't really pay attention to mpg. I see differences between me and my wife a lot but that's another storry. Also the car feels slower after my wife drives it. Thanks to the adaptive ECU.

I think it is hard to measure mpg just by feel. So many variables. Especially short distances.

[telcoman]

Say what?

So....Last Thrusday I drove one of my normal routes for meetings and decided to watch my mpg. At 75-80mph I was running around 23.xMPG. At 60-65 I was getting up to 28.7MPG. On Monday I did the same trip and at 80MPH I was around 21-23MPG and at 60-65 I maxed at 25.xMPG. Now, weather was relatively the same as both days were clear, relatively no wind, and I left at appx the same time each morning. Traffic was the same both days and I was watching the mileage at appx the same locations each time.

I have also noticed that on some days the G feels slower than others. I have not been able to map out what the differences are as some days seem humid and cool while others are dry and warm.

Anyone else notice this? I noticed MPG differences like the above in my Maxima but never really experienced where the vehicle felt faster on some days.

I keep a spreadsheet that currently has 509 entrys in it beginning with my date of purchase 12/31/05.
I record every fill up and every repair and parts purchase.
The correct and most accurate way to measure MPG is from fill up to fillup. Divide the gallons to fill up into the miles traveled between fillups to obtain MPG.
Mileage is affected by temperature, humdity, speed, windows up or down and driving style etc.
You are viewing a readout from a vacuum sensor which is not as accurate as calculating the MPG as described above over a tankful of fuel.

Telcoman

[audtatious]

I keep a spreadsheet that currently has 509 entrys in it beginning with my date of purchase 12/31/05.
I record every fill up and every repair and parts purchase.
The correct and most accurate way to measure MPG is from fill up to fillup. Divide the gallons to fill up into the miles traveled between fillups to obtain MPG.
Mileage is affected by temperature, humdity, speed, windows up or down and driving style etc.
You are viewing a readout from a vacuum sensor which is not as accurate as calculating the MPG as described above over a tankful of fuel.

Telcoman

Yeah....I could keep a spreadsheet but I usually don't worry about mileage/mpg. I just thought I would see what I'm doing on my trips the last couple weeks.

Yes, the in-car mpg calculator is usually off +/- some percentage.

[terrycs]

I keep a spreadsheet that currently has 509 entrys in it beginning with my date of purchase 12/31/05.
I record every fill up and every repair and parts purchase.
The correct and most accurate way to measure MPG is from fill up to fillup. Divide the gallons to fill up into the miles traveled between fillups to obtain MPG.
Mileage is affected by temperature, humdity, speed, windows up or down and driving style etc.
You are viewing a readout from a vacuum sensor which is not as accurate as calculating the MPG as described above over a tankful of fuel.

Telcoman

Yeah....I could keep a spreadsheet but I usually don't worry about mileage/mpg. I just thought I would see what I'm doing on my trips the last couple weeks.

Yes, the in-car mpg calculator is usually off +/- some percentage.

The in car calculations are actually correct and very accurate. BUT .. it calculates based on the recent injector duty cycle (for fuel flow rate). Same goes true for "distance to empty". Check out the reading after you floor it a few times before resetting it. I think I've gotten mine down to 9 mpg.

Like other have said, it's usually better to calculate on a spreadsheet because it averages over the full tank.

[audtatious]

Thanks

Too much effort for something I'm not _that_ interested in. I was more curious of others experiences than anything.

[leeG35]

MPG? There's an app for that.

So many things can affect mileage. Temperature, wind, weight, tire pressure, road surface, distance traveled between start to shut down and the list just goes on. I agree it's best to monitor mileage from fill-up to fill-up. Instantaneous mileage from the trip computer is all over the map.

I have 65,000 miles of fuel use records. The best my G35 coupe has achieved is 26.9 mpg fully loaded (two people plus luggage) on a long trip at a steady 70 mph. The worst was 15.0 mpg local driving up and down hills with frequent stops.

Overall average is 22.5.

[telcoman]

Yeah....I could keep a spreadsheet but I usually don't worry about mileage/mpg. I just thought I would see what I'm doing on my trips the last couple weeks.

Yes, the in-car mpg calculator is usually off +/- some percentage.[/quote]

The in car calculations are actually correct and very accurate. BUT .. it calculates based on the recent injector duty cycle (for fuel flow rate). Same goes true for "distance to empty". Check out the reading after you floor it a few times before resetting it. I think I've gotten mine down to 9 mpg.

Like other have said, it's usually better to calculate on a spreadsheet because it averages over the full tank.[/quote]

Here is a snapshot from a 2010 G37X loaner that I drove for two days



Telcoman

[audtatious]

That's low, even for me

[sniper27]

20.8 is the highest i've gotten. about 50/50 city/highway with lots of traffic in S. Cal.

[audtatious]

I'm 80%+ highway. Mine usually shows around 22.