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Discussion Starter · #1 ·
Since buying the 2021, I've reset the drive computer fuel/travel data three times. The first was after a month of ownership, and the MPG was 30.3 with an average MPH of 31.

Two weeks after the reset, MPG was 30.5, with an average MPH of 31.

After resetting it three days ago, the MPG was 32.7 with MPH at 32.

I think it was MuranoSL2003 who mentioned something about the computer being optimistic with its fuel estimates by something like 8-10%. It really doesn't seem possible that this car is getting a mixed MPG of above 27, when highway MPG is supposed to be 27. Also, I'm pretty sure my average speed over the past few days has been around 45. I did a quick reset this morning while cruising along, unstopped, at 60-70MPH for about 20 minutes, then I drove for about another 15 minutes at speeds typically from 30-42. Along the way at slower speeds, I had to stop a couple of times at a stop sign for a few seconds, or slow to below 30MPH for maybe 20 seconds here and there, but by my estimates, there's no way the average speed is 31.

Does everyone's 3rd Gen data seem off?
 

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I haven't gone to the extreme like you have but i traded a 15 SL and got a 21 SL and it seems like i am getting better gas mileage with the 21. The 15 i seem to have gotten around 19 to 21 mpg for the city driving, witch is a lot of express way driving, with the 21 it appears that it has gone up to 21 to 23 mpg. this is with short drives, but when i go more that 10-20 miles the mileage seems to jump up to around 23 to 25 mpg. I only have just over 1k so far.
 

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I found this just by googling nissan key link.
 

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Keep a real log for a couple of fill-ups - like back in the old days before all of this new-fangled computer tomfoolery. :)

Just jot down the miles at fill up and how many gallons you put in, and repeat a few times. You can then subtract the previous miles from the current miles to get miles travelled between fill-ups, and then divide the miles by gallons of gas you just put in and presto - your actual MPG.

To get really fancy, reset the computer when you fill up and see how close it is to the actual math on the next fill up.
 

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Discussion Starter · #5 ·
I could do it manually, but I'm not really concerned about fuel economy. The car gets what it gets. I was more curious to know if everybody's computer estimations were this good (or off by a lot.) Unless done intentionally by Nissan to make the driver feel they're getting better MPG than they actually are, I really can't understand why the computer would be wrong. Seems to me it's a simple formula used to calculate this stuff, so why should it be wrong? Maybe MO21 is actually getting 31+ mixed MPG. Using the A/C for most of the time over the last 3-4 days due to temps in the mid 90s, I expected the MPG to come down dramatically, but it's barely moved from where it usually is.
 

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Discussion Starter · #6 · (Edited)
I wonder if the factors used to provide MPG data aren't simply gallons and miles. In my 2003, I'd be willing to bet it was a simple equation, which is why the MPG always seemed realisitic. In this new 2021 that also shows the amount of time the car is running, perhaps that's also factored in. More to the point, perhaps Nissan engineers determined that at hot idle, the best MPG the Murano-specific engine setup was able to achieve was 36, under very specific and controlled conditions. Perhaps that number comes into play everytime the car isn't moving (i.e. is at 0 MPH) and the drive computer keeps track of that duration which is then brought into the formula, which might explain why the MPG is so fantastic. Additionally, what if there's programming that tells the computer to degrade certain figures over time or at certain mileage intervals (say, every 5000 miles) so that as the car and its parts age, it makes it seem like a natural occurrence to the driver? Maybe in the beginning, Nissan wants MO owners to feel really great about their purchase, so the numbers are skewed to look impressive early on. Then, years later, reality appears and maybe this would trigger someone to decide it's time to trade it in for a new Nissan. :) The last part is purely conspiracy theory that I just thought of while writing this.

Doing some testing over the past couple of days, I noticed if I reset the drive computer while at a speed I can travel at for some distance without slowing, the MPG would stay around 26.5 (with A/C on), and 28 (with A/C off), which seems accurate. As soon as I put some hot idle time on the engine, the MPG jumped to the 29-30 range, and then hours later went to 31.5 after not resetting anything. I'm sure that sitting at idle is saving more fuel than driving, but I'm not so sure it would result in the kind of fuel savings the DC is suggesting.
 

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Discussion Starter · #8 ·
After disconnecting the NEG battery cable for about five minutes last night in an attempt to clear the persistent warning message of a loose fuel cap, I noticed today that MO no longer shows an unrealistic MPG of 30-32, but is staying around 26.5. I wonder if removing the NEG cable cleared some software glitch or static memory problem and now things are better. Time will tell.
 

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