Mostly unscientific gas mileage observations - YMMV

[pfletcher229648]

DISCLAIMER:
Let me just state I do not, repeat DO NOT stand behind any of these numbers, simply putting this here for conversation.

GENERAL INFO:
I am of the lost Gen X generation and have hit my mid-fifties, and have developed a lesser desire for high speeds. Mostly because I now drive a Jeep Wrangler. If I still drove a sports car, I would likely still be driving at much higher speeds. However, the Wrangler was not built for speed, it is a large square chunk of metal that doesn’t appreciate high speeds, especially high speed cornering. So I have slowed down considerably in my daily driving. On the interstates I utilize the Active Cruise Control on the Wrangler and typically just put it around 68 and drive in the right hand lane. I find this to get me optimal gas mileage and interstate driving is much more relaxing as the vehicle speeds up and slows down with traffic without requiring much input from me.

HYPOTHESIS:
Drafting behind bigger objects while traveling in a Wrangler can increase MPG.

EXPERIMENT SETUP:
Just got back from picking up our new 2024 Wrangler Rubicon X from an out of state dealer. On the roughly 600 mile trek back home I observed about 18.4 MPG average. The gas mileage estimate on flat roads generally showed about 18 to 19 current MPG. On one particular stretch of I-95 I was traveling in the right hand lane and had the cruise control set on 67 with the follow-behind meter set on two. Don’t like to tailgate people but also don’t like to leave too much room as everybody and their brother cuts in between you and the car in front of you. I find this setting gives me enough room just in case the vehicle in front of me does something drastic or incredibly stupid.

OBSERVATION:
Anyway, after setting the cruise control on 67 and setting a safe distance behind the 18 wheeler in front of me, I noticed the current MPG estimate rose up from it’s normal 18 to 19 MPG to 23 to 24 MPG. As long as we were traveling at a consistent speed and on a flat stretch of road the MPG stayed pretty consistent at or slightly above 23 MPG. After traveling this way for a 10 miles or so I noticed my average trip MPG started climbing from its fairly consistent 18.4. After some distance it went over 19 and eventually hit 19.5.

CONCLUSION:
This Jeep Wrangler is a massive block of machinery that consumes massive amounts of petrol when forcing itself along down the road at highway speeds. When drafting behind a much larger object that is punching a much bigger hole in the atmosphere it’s able to enjoy a somewhat decent increase in MPG. Now, 20 MPG is nothing to get really excited about. However, the prospect of gaining a 20% increase in fuel consumption on a road trip appeals to me on several levels, the least of which is I’m cheap, and due to our current circumstance caused by whatever opinions you may politically subscribe to , we find ourselves in a period of time when gas is not.

Just one man’s observations, YMMV.

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[Dgr401]

I have noticed the same effect driving to Florida. I had a Ford Focus that got 27-28 mpg on the highway, was behind a truck and the mileage went to 34mpg. I was not that close to the truck but it still made quite a difference in my mpg’s.

 

[Ratbert]

As always: drafting behind a semi improves mileage, significantly reduces visibility, and increases the damage to the Jeep's body and windshield from rocks.

I'm thinking that it's not all aerodynamics and you're negatively impacting the semi, but I obviously could be wrong.

p.s. most of us avoid using cruise too much during break-in.

 

[2nd 392]

Yep— drafting a big rig improves mpg. Too bad you can’t see what he does that might cause him to panic stop.

paying for the extra gas recommended.This old trucker has seen many of these. The MC riders head was far from his body and I got to watch.

 

[Ratbert]

Yep— drafting a big rig improves mpg. Too bad you can’t see what he does that might cause him to panic stop.

paying for the extra gas recommended.This old trucker has seen many of these. The MC riders head was far from his body and I got to watch.

His adaptive cruise should mostly mitigate that concern.

 

[2nd 392]

His adaptive cruise should mostly mitigate that concern.

For a normal stop yes, but if you are close and he locks them up or suddenly swerves nope, insufficient time for the distance required to stop. Even with the computer beating your reaction time……. I managed to swerve into the fortunately open left lane around a stall, the vehicle closely following me in the fog hit the stall causing a chain reaction pile up that got front page headlines. HWY 99 closed at the Kings river bridge for the extended cleanup. There were fatalities and injuries.

 

[Ratbert]

For a normal stop yes, but if you are close and he locks them up or suddenly swerves nope, insufficient time for the distance required to stop. Even with the computer beating your reaction time……. I managed to swerve into the fortunately open left lane around a stall, the vehicle closely following me in the fog hit the stall causing a chain reaction pile up that got front page headlines. HWY 99 closed at the Kings river bridge for the extended cleanup.

But he won't be "too close" when using ACC. But then again if he's using it like intended then he's not really drafting.

 

[2nd 392]

But he won't be "too close" when using ACC. But then again if he's using it like intended then he's not really drafting.

I tried to use it set for a large distance. Idgets constantly pulling into the space with the resulting auto braking and slow down. I gave up using it unless thin well moving traffic.

 

[Dgr401]

You don’t need to get close to get a benefit from the other vehicle.

 

[Ratbert]

I tried to use it set for a large distance. Idgets constantly pulling into the space with the resulting auto braking and slow down. I gave up using it unless thin well moving traffic.

Man, I use it nearly all the time. The closest setting (3-ish seconds?) works well on the interstate and the next is more appropriate just about everywhere else.

Definitely a game-changer for long trips. Over 31k miles in a year and a half...and I work from home.

 

[2nd 392]

Man, I use it nearly all the time. The closest setting (3-ish seconds?) works well on the interstate and the next is more appropriate just about everywhere else.

Definitely a game-changer for long trips. Over 31k miles in a year and a half...and I work from home.

Agree on the open road I appreciate it. Most of my HWY driving is within 5 close together towns and I seldom use it or even the normal CC…. Retired- formerly an ~ 130 mi rt commute.

 

[Bandit59]

DISCLAIMER:
Let me just state I do not, repeat DO NOT stand behind any of these numbers, simply putting this here for conversation.

GENERAL INFO:
I am of the lost Gen X generation and have hit my mid-fifties, and have developed a lesser desire for high speeds. Mostly because I now drive a Jeep Wrangler. If I still drove a sports car, I would likely still be driving at much higher speeds. However, the Wrangler was not built for speed, it is a large square chunk of metal that doesn’t appreciate high speeds, especially high speed cornering. So I have slowed down considerably in my daily driving. On the interstates I utilize the Active Cruise Control on the Wrangler and typically just put it around 68 and drive in the right hand lane. I find this to get me optimal gas mileage and interstate driving is much more relaxing as the vehicle speeds up and slows down with traffic without requiring much input from me.

HYPOTHESIS:
Drafting behind bigger objects while traveling in a Wrangler can increase MPG.

EXPERIMENT SETUP:
Just got back from picking up our new 2024 Wrangler Rubicon X from an out of state dealer. On the roughly 600 mile trek back home I observed about 18.4 MPG average. The gas mileage estimate on flat roads generally showed about 18 to 19 current MPG. On one particular stretch of I-95 I was traveling in the right hand lane and had the cruise control set on 67 with the follow-behind meter set on two. Don’t like to tailgate people but also don’t like to leave too much room as everybody and their brother cuts in between you and the car in front of you. I find this setting gives me enough room just in case the vehicle in front of me does something drastic or incredibly stupid.

OBSERVATION:
Anyway, after setting the cruise control on 67 and setting a safe distance behind the 18 wheeler in front of me, I noticed the current MPG estimate rose up from it’s normal 18 to 19 MPG to 23 to 24 MPG. As long as we were traveling at a consistent speed and on a flat stretch of road the MPG stayed pretty consistent at or slightly above 23 MPG. After traveling this way for a 10 miles or so I noticed my average trip MPG started climbing from its fairly consistent 18.4. After some distance it went over 19 and eventually hit 19.5.

CONCLUSION:
This Jeep Wrangler is a massive block of machinery that consumes massive amounts of petrol when forcing itself along down the road at highway speeds. When drafting behind a much larger object that is punching a much bigger hole in the atmosphere it’s able to enjoy a somewhat decent increase in MPG. Now, 20 MPG is nothing to get really excited about. However, the prospect of gaining a 20% increase in fuel consumption on a road trip appeals to me on several levels, the least of which is I’m cheap, and due to our current circumstance caused by whatever opinions you may politically subscribe to , we find ourselves in a period of time when gas is not.
I don’t doubt it helps. But mine gets 23-24 on my last trip to Myrtle Beach. I travel 70 with cruise on. But I did not buy it for mpg.
Just one man’s observations, YMMV.

 

[pfletcher229648]

Man, I use it nearly all the time. The closest setting (3-ish seconds?) works well on the interstate and the next is more appropriate just about everywhere else.

Definitely a game-changer for long trips. Over 31k miles in a year and a half...and I work from home.

Thanks for keeping it rational Ratbert. Like I said folks, I don’t tailgate. I never play footsie with 18 wheelers. I respect the hell out of them and F=MA.

I always keep the setting on two or three bars, depending on conditions and traffic. I always keep my eyes on the road and my foot and hands ready. I do however find ACC to take a lot of the fatigue from long highway drives especially in heavy traffic and less than ideal conditions.

My point and topic is more about does anyone else see gains in this or is it all in my head. My 2022 Rubicon was my first vehicle that I daily drive that has ACC. I just never thought riding at a SAFE distance behind another vehicle would result in a drafting affect and increased MPG. I always thought one had to be way to close for comfort to see benefits of drafting.

 

[78cj7-18lj]

DISCLAIMER:
Let me just state I do not, repeat DO NOT stand behind any of these numbers, simply putting this here for conversation.

GENERAL INFO:
I am of the lost Gen X generation and have hit my mid-fifties, and have developed a lesser desire for high speeds. Mostly because I now drive a Jeep Wrangler. If I still drove a sports car, I would likely still be driving at much higher speeds. However, the Wrangler was not built for speed, it is a large square chunk of metal that doesn’t appreciate high speeds, especially high speed cornering. So I have slowed down considerably in my daily driving. On the interstates I utilize the Active Cruise Control on the Wrangler and typically just put it around 68 and drive in the right hand lane. I find this to get me optimal gas mileage and interstate driving is much more relaxing as the vehicle speeds up and slows down with traffic without requiring much input from me.

HYPOTHESIS:
Drafting behind bigger objects while traveling in a Wrangler can increase MPG.

EXPERIMENT SETUP:
Just got back from picking up our new 2024 Wrangler Rubicon X from an out of state dealer. On the roughly 600 mile trek back home I observed about 18.4 MPG average. The gas mileage estimate on flat roads generally showed about 18 to 19 current MPG. On one particular stretch of I-95 I was traveling in the right hand lane and had the cruise control set on 67 with the follow-behind meter set on two. Don’t like to tailgate people but also don’t like to leave too much room as everybody and their brother cuts in between you and the car in front of you. I find this setting gives me enough room just in case the vehicle in front of me does something drastic or incredibly stupid.

OBSERVATION:
Anyway, after setting the cruise control on 67 and setting a safe distance behind the 18 wheeler in front of me, I noticed the current MPG estimate rose up from it’s normal 18 to 19 MPG to 23 to 24 MPG. As long as we were traveling at a consistent speed and on a flat stretch of road the MPG stayed pretty consistent at or slightly above 23 MPG. After traveling this way for a 10 miles or so I noticed my average trip MPG started climbing from its fairly consistent 18.4. After some distance it went over 19 and eventually hit 19.5.

CONCLUSION:
This Jeep Wrangler is a massive block of machinery that consumes massive amounts of petrol when forcing itself along down the road at highway speeds. When drafting behind a much larger object that is punching a much bigger hole in the atmosphere it’s able to enjoy a somewhat decent increase in MPG. Now, 20 MPG is nothing to get really excited about. However, the prospect of gaining a 20% increase in fuel consumption on a road trip appeals to me on several levels, the least of which is I’m cheap, and due to our current circumstance caused by whatever opinions you may politically subscribe to , we find ourselves in a period of time when gas is not.

Just one man’s observations, YMMV.

If you decide to draft behind a big truck make sure that you can see its mirrors. If you can see its mirror then the driver can see you. Bad sh#+ can happen fast with big trucks.

 

[laroo]

Man, I use it nearly all the time. The closest setting (3-ish seconds?) works well on the interstate and the next is more appropriate just about everywhere else.

Definitely a game-changer for long trips. Over 31k miles in a year and a half...and I work from home.

I don't have ACC in my Jeep, because I've always hated it (and I'm a cheap bastard). My wife has had it for a few years, and I turn it off every time on a long trip. However, I forced myself to use it (and slow down) last summer on an 8 hour trip, and I swear I arrived with blood pressure at least 20 points below normal. It was so much less stressful, and it made me a believer. Now I wish I would have ordered it for mine.

My take is... if you're driving 10+ mph over the speed limit, it's just aggravating. Knock that down to 0-5 over the limit, and it is a game changer.

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