And your test mule is a 2dr which is 500 lbs lighter then the 4 door so the results would be even worse had you done your testing on the 4 door JLU.
0.4 mpg difference is ~5% error, which not bad IMO. You have confirmed my belief that ESS is more trouble than it's worth. Thanks for doing the science!Fellow Jeep enthusiasts, over the first two years of owning my Jeep I have recorded every tank of gas put into it. The data I have recorded includes number of gallons pumped, miles driven per trip odometer "A", average fuel economy per trip odometer "A", date, and observed fuel economy per total miles actually driven divided by actual gallons put into the jeep (in other words, real hand-calculated MPG). Armed with this data I present the following for the betterment of the community.
First, the BLUF: Over 122 tanks of gas (really, 110 as I will explain below) I averaged 17.8 mpg on the first half while disabling ESS and 18.0 mpg on the second half while leaving ESS enabled as per the jeep's default. According to my math -which could be complete garbage- I saved about 10 gallons of fuel on the second half of this experiment. On average the computer was 0.4 mpg too optimistic compared to the observed, hand-calculated MPG. Now, on to some of the details.
Subject matter
2019 Jeep Wrangler Rubicon
- Manual Transmission
- Steel Bumper Group
- LED Headlights
- Painted fender flares
- No other factory options and no aftermarket mods - the jeep remained completely stock through the entire test period
Methodology
The testing period began on 22 April 2019 when I took delivery of the jeep and ended on 14 May 2021 when I put the 122nd tank of gas in it, just over two years later. I implemented a number of control measures to decrease variables in the conduct of data collection:
Below is a sample of the data from my excel spreadsheet:
- Every tank was filled with Regular Unleaded 87 octane fuel
- My commute typically included 46 miles of interstate highway driving and 14 miles of country roads / city street / mixed roads
- Pure highway tanks greatly exceeded the 17.9 mpg average, but I don't take many road trips. Even though my daily commute had a good amount of highway miles there was still a lot of short range, slow driving mixed in
- I filled every tank up until the first "click" then attempted to top it off exactly one time. This extra top-off had to have real fuel flow, not just the backpressure-restricted weak flow immediately following the first "click"
- The last few drops of fuel would be shaken out of the fuel filler nozzle
- Each receipt was collected from the pump and the following written on each receipt:
- Tank X (X = 1, 2, 3, 4, or whatever number tank it was)
- Y miles (Y = miles driven on that tank from trip odometer "A")
- Z mpg (c) (Z = mpg as reported by trip odometer "A")(The "c" in parenthesis means computer)
- If, for some reason, I was unable to collect a receipt from the pump or the attendant inside (i.e. if I was too lazy to go inside) I would write all the above data on the previous tank's receipt plus date, gas station location, gallons of fuel pumped, and USD spent on fuel
- Trip odometer "A" was reset before turning the Jeep on to ensure that all fuel burned post-filling counted against the next tank
- All data was entered into an excel spreadsheet which used an equation to calculate MPG (observed) and the delta between MPG (c) and MPG (o)
- Every effort was made to avoid "short" tanks. I would usually fill up when the indicator said 25-40 miles of range remaining but didn't worry too much about it
- The entire testing period took place in Texas. The length of the test ensured that data was collected for both ESS and non-ESS in all weather and driving conditions
- On tanks 1-61, ESS was disabled religiously. Part of my turning-on-the-jeep ritual was hitting the ESS button. Breaking this habit proved very difficult for the first few tanks of the 62-122 set of tanks
- On tanks 62-122, I did my best to allow ESS to work as intended to gain the most benefit from it
- Of the 122 tanks collected, I discarded the top 3 and bottom 3 observed MPG tanks for both ESS and non-ESS categories, resulting in 110 total tanks analyzed
Conclusions
- Over the course of 30,435.5 miles, the difference between 17.8 mpg and 18.0 mpg is 18.99 gallons, or $54.12 with the current gas prices near me. Not worth it. Going forward I'll go back to disabling ESS like I did on tanks 1 through 61
- ESS really isn't that annoying. The worst part about it is the climate control losing its effectiveness in the heat or cold. But again, not worth it to me, especially considering it may cause unnecessary wear on the starter
- Don't trust the computer to tell you accurate mileage. Most of the time it was overly optimistic, and as stated in the BLUF, it was off by 0.4 mpg on average
- 2-door Rubicon doesn't get good gas mileage
- I reserve the right to edit the shit out of this post if I made egregious errors
- YMMV
I think you’re generally correct on most points.
Thank you, sir. Frankly, my knowledge of bearings is the least of the bunch but my understanding is that they're better than they've ever been. I think we're in an odd time with batteries because while they're improved, they're still lead acid. There's much better battery tech out there but the EV market is glomming them all up. Not to mention that I definitely look sideways at the JL's puny Aux battery. That has a lot of room for improvement.
While you're right on some counts, you definitely cant say the negative effect of ESS is zero. Even if the starter lasts 10x as long as they used to (doubt it), its still going to fail earlier. I dont know about you, but my ess would activate at least 20 times on most drives if I left it on. Thats 20x more starts and wear on the starter. Even with good oil, zero oil pressure is still zero, and starts are where most of the internal wear is going to happen. For the extremely negligible fuel economy increase its still not worth it in my humble opinion.
What's your big concern with oil pressure? It's an operational start, not a cold start. Everything is still well lubricated with oil. Lines haven't drained. Engine is warm. Starters don't fail like they used to. What's the problem?
I respect your opinion but I can’t see how you’d say “lines haven’t drained” at a 45 second red light. You have a point with fully synthetic oil leaving everything smooth but I’m not convinced that’s enough.
With E Torque it’s a smarter, less wear, smoother restart avenue IF you can utilize the start/stop. I believe I read in the past year that unless the engine shuts down for at least 5 secs each instance, there’s no gain to start/stop for whatever that’s worth. Makes sense though.
What is your ratio of highway to city driving? If its something like 90% highway then you wouldn't get much benefit out of ESS to start with.Fellow Jeep enthusiasts, over the first two years of owning my Jeep I have recorded every tank of gas put into it. The data I have recorded includes number of gallons pumped, miles driven per trip odometer "A", average fuel economy per trip odometer "A", date, and observed fuel economy per total miles actually driven divided by actual gallons put into the jeep (in other words, real hand-calculated MPG). Armed with this data I present the following for the betterment of the community.
First, the BLUF: Over 122 tanks of gas (really, 110 as I will explain below) I averaged 17.8 mpg on the first half while disabling ESS and 18.0 mpg on the second half while leaving ESS enabled as per the jeep's default. According to my math -which could be complete garbage- I saved about 10 gallons of fuel on the second half of this experiment. On average the computer was 0.4 mpg too optimistic compared to the observed, hand-calculated MPG. Now, on to some of the details.
Subject matter
2019 Jeep Wrangler Rubicon
- Manual Transmission
- Steel Bumper Group
- LED Headlights
- Painted fender flares
- No other factory options and no aftermarket mods - the jeep remained completely stock through the entire test period
Methodology
The testing period began on 22 April 2019 when I took delivery of the jeep and ended on 14 May 2021 when I put the 122nd tank of gas in it, just over two years later. I implemented a number of control measures to decrease variables in the conduct of data collection:
Below is a sample of the data from my excel spreadsheet:
- Every tank was filled with Regular Unleaded 87 octane fuel
- My commute typically included 46 miles of interstate highway driving and 14 miles of country roads / city street / mixed roads
- Pure highway tanks greatly exceeded the 17.9 mpg average, but I don't take many road trips. Even though my daily commute had a good amount of highway miles there was still a lot of short range, slow driving mixed in
- I filled every tank up until the first "click" then attempted to top it off exactly one time. This extra top-off had to have real fuel flow, not just the backpressure-restricted weak flow immediately following the first "click"
- The last few drops of fuel would be shaken out of the fuel filler nozzle
- Each receipt was collected from the pump and the following written on each receipt:
- Tank X (X = 1, 2, 3, 4, or whatever number tank it was)
- Y miles (Y = miles driven on that tank from trip odometer "A")
- Z mpg (c) (Z = mpg as reported by trip odometer "A")(The "c" in parenthesis means computer)
- If, for some reason, I was unable to collect a receipt from the pump or the attendant inside (i.e. if I was too lazy to go inside) I would write all the above data on the previous tank's receipt plus date, gas station location, gallons of fuel pumped, and USD spent on fuel
- Trip odometer "A" was reset before turning the Jeep on to ensure that all fuel burned post-filling counted against the next tank
- All data was entered into an excel spreadsheet which used an equation to calculate MPG (observed) and the delta between MPG (c) and MPG (o)
- Every effort was made to avoid "short" tanks. I would usually fill up when the indicator said 25-40 miles of range remaining but didn't worry too much about it
- The entire testing period took place in Texas. The length of the test ensured that data was collected for both ESS and non-ESS in all weather and driving conditions
- On tanks 1-61, ESS was disabled religiously. Part of my turning-on-the-jeep ritual was hitting the ESS button. Breaking this habit proved very difficult for the first few tanks of the 62-122 set of tanks
- On tanks 62-122, I did my best to allow ESS to work as intended to gain the most benefit from it
- Of the 122 tanks collected, I discarded the top 3 and bottom 3 observed MPG tanks for both ESS and non-ESS categories, resulting in 110 total tanks analyzed
Conclusions
- Over the course of 30,435.5 miles, the difference between 17.8 mpg and 18.0 mpg is 18.99 gallons, or $54.12 with the current gas prices near me. Not worth it. Going forward I'll go back to disabling ESS like I did on tanks 1 through 61
- ESS really isn't that annoying. The worst part about it is the climate control losing its effectiveness in the heat or cold. But again, not worth it to me, especially considering it may cause unnecessary wear on the starter
- Don't trust the computer to tell you accurate mileage. Most of the time it was overly optimistic, and as stated in the BLUF, it was off by 0.4 mpg on average
- 2-door Rubicon doesn't get good gas mileage
- I reserve the right to edit the shit out of this post if I made egregious errors
- YMMV
) vs when it is working.
