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Discussion Starter #1
I'm impressed with adaptive cruise in the Colorado mountains on steep downgrades.

I have ObdCheck so I know when brakes are being applied, obd matches the red tail lights in the adaptive display, so I know the engine braking I'm feeling is real.

I find that adaptive cruise can produce significantly more engine braking than I can using manual.

Adaptive provides significantly more engine braking at a lower rpm, I'm wondering if adaptive can " shut down " the engine more than just no pressure on accelerator pedal when I'm attempting manual downshifts.

This is real egine braking, the brakes are only in play for max deceleration.

I haven't worded this in the best technical manner, but hope that someone can provide more info.

I never used cruise control in the mountains in previous vehicles, but use adaptive most of the time for mountains now in normal driving conditions. Winter conditions require much more caution, so no cruise in snow and ice.
 

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2015 Outback 3.6R with Eyesight
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I'm impressed with adaptive cruise in the Colorado mountains on steep downgrades.

I have ObdCheck so I know when brakes are being applied, obd matches the red tail lights in the adaptive display, so I know the engine braking I'm feeling is real.

I find that adaptive cruise can produce significantly more engine braking than I can using manual.

Adaptive provides significantly more engine braking at a lower rpm, I'm wondering if adaptive can " shut down " the engine more than just no pressure on accelerator pedal when I'm attempting manual downshifts.

This is real egine braking, the brakes are only in play for max deceleration.

I haven't worded this in the best technical manner, but hope that someone can provide more info.

I never used cruise control in the mountains in previous vehicles, but use adaptive most of the time for mountains now in normal driving conditions. Winter conditions require much more caution, so no cruise in snow and ice.
This does not match my experience. On the same steep downhill that I drove home from work everyday I experimented with manual shifting vs cruise control and they seemed the same. The cruise control will also use the brakes (the brake light in the car ion on the dash lights up).
 

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Discussion Starter #3
Thanks for your comments

Guess our " mileage must vary ".

On a long 5 mile 7% downslope that I drive, adaptive cruise set at 55mph holds car at that speed with rpms around 3k with no use of wheel brakes.. If I use manual shifters rpm is up near 5k and I still have to use wheel braking occasionally. Staying in manual gear that is in 3k range means even more use of wheel brakes.

It just " feels like" adaptive can create extra engine braking at a given rpm.
I've driven large Suvs that let you select 4cyl or 8cyl engine braking.

I wonder if adaptive has ability to shutdown down engine more than happens when foot is just off of acelerator?
 

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2018 Outback 2.5 Touring
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So I have had my '18 OB for a week now and driving in North Jersey in some of the hilly areas, I have been quite satisfied with the ACC holding my speed at where I have it set. I actually have more an issue with the lead car not holding their speed consistently leading the ACC speeding up and then jamming on the brakes.

OT: Is there an adjustable setting for the ACC on the speed of acceleration? I feel like I would want it to be just a tad slower at accelerating to save some MPG.
 

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2015 3.6R Limited w/ES
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^ no such adjustment I'm aware of.

I've noticed the same thing as the OP, to the point of making me wonder if the brake indicators in the cluster display are completely accurate. Can I get more braking than ACC by simply downshifting? Yes, of course, ACC will sooner use the brakes than drive up the RPMs to any significant degree. There certainly seems to be something the ACC is doing to get more engine braking without noticeably revving the engine (perhaps it just has finer control of the CVT?).
 

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Discussion Starter #6
I'm pretty sure that the red brake light on the adaptive display is accurate. I have an obd box that shows brake activity, it matches red light on dash.

Manual downshifting, with rpms up in the 5k range, does not provide as much engine braking as adaptive can get in the 3k range.

So I'm guessing that adaptive can somehow get more engine braking by " turning off " the engine than happens when foot is off accelerator.
 

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I'm pretty sure that the red brake light on the adaptive display is accurate. I have an obd box that shows brake activity, it matches red light on dash.
Yep, you made that quite clear in your OP, which is why I mentioned it.

Manual downshifting, with rpms up in the 5k range, does not provide as much engine braking as adaptive can get in the 3k range.
Haven't carefully compared, but I'm fairly certain that's not the case with my 3.6R.

So I'm guessing that adaptive can somehow get more engine braking by " turning off " the engine than happens when foot is off accelerator.
Not sure what you mean by that, but my engine is always running.
 

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Right, fuel injectors open back up to prevent a stall, i.e., the engine is always running. Still don't see how that would explain the ability of ACC to apply more engine braking than when I coast the engine (or downshift, at least to some extent). My assumption has always been that there's actually no difference, and something else is giving me the impression of more engine braking. It's not a terribly dramatic effect in my vehicle.
 

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^ no such adjustment I'm aware of.

I've noticed the same thing as the OP, to the point of making me wonder if the brake indicators in the cluster display are completely accurate. Can I get more braking than ACC by simply downshifting? Yes, of course, ACC will sooner use the brakes than drive up the RPMs to any significant degree. There certainly seems to be something the ACC is doing to get more engine braking without noticeably revving the engine (perhaps it just has finer control of the CVT?).
I've wondered if the dash display (or illumnating the brake lights) happens in all cases when ACC is applying the brakes, i feel like they are not directly linked. When traction control applies brakes the red lights do not turn on, ACC could very easily use some logic to decide if the degree of braking requires illuminating the brake lights and only illuminate in those conditions.
 

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@dat2109 - Well, traction control (or torque vectoring) isn't braking all 4 wheels, so that makes sense. The fact that the OP verified no brake signal from the OBD port would seem to prove otherwise. I'd also expect the brake system, being critical to vehicle safety, would require that the tail lights always activate when any amount of standard braking is applied.
 

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I get enough road salt corrosion to the rotors in my Vermont driveway that I can hear the brakes if the car has been sitting for a couple of days.

Anyways, I have a somewhat different use case. At the end of the ski day, I drive a mile down a 35 mph posted paved ski area access road to my driveway. The state police are "enthusiastic" about pulling over anyone exceeding the speed limit so I obey the posted speed limit sign like it's chiseled on stone tablets and carried down from the mountain.

The road is steep enough that the ACC applies the brakes. I can hear it because of the rust on the rotors. To save my brake pads, I use the paddle shifter to control my speed. I've written about this issue a few times here over the years. For something that is the de-facto standard ski/mountain car with all the fancy gizmo off roading buttons, this behavior is not what you'd expect. This is a 2015. Maybe they've changed the programming in newer model year Outbacks but that's the behavior I observe. I've always had to manually downshift in manual transmission cars, PRND32L slush-o-matics, and my VW GTI DSG dual clutch automatic so it's no big deal. It would be nice to be able to set the ACC to 35 mph and have it engine brake. It holds speed with the paddle shifter at 4500 RPM.
 

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Guess our " mileage must vary ".

On a long 5 mile 7% downslope that I drive, adaptive cruise set at 55mph holds car at that speed with rpms around 3k with no use of wheel brakes.. If I use manual shifters rpm is up near 5k and I still have to use wheel braking occasionally. Staying in manual gear that is in 3k range means even more use of wheel brakes.

It just " feels like" adaptive can create extra engine braking at a given rpm.
I've driven large Suvs that let you select 4cyl or 8cyl engine braking.

I wonder if adaptive has ability to shutdown down engine more than happens when foot is just off of acelerator?
7% grade and 55 mph, you probably have enough wind resistance that the engine braking done by the ACC is sufficient to hold speed. At lower speeds on a steeper hill, the ACC applies the brakes.

I'll play with mine over the next couple of months. I'll bet the ACC has a maximum RPM for engine braking. You can probably get more engine braking at higher RPM using the paddle shifters than the ACC will do automatically. I've never watched the tach to see the RPM it allows.
 

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I am kind of liking the engine braking that ACC applies on hills for my OB '18. I have not owned a lot of vehicles, but this is my first that I have really seen a "car" do that on cruise.

The OB I am sure has its thresholds for ACC engine braking. Again, I like it especially for a road that I am not familiar with and coming into corners going the speed limit provides a degree of safety/caution that I like.

Some folks however may not like the engine braking as it will eat into your fuel economy versus just coasting down the hill and letting gravity take you for a bit. To each their own.
 

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I am kind of liking the engine braking that ACC applies on hills for my OB '18. I have not owned a lot of vehicles, but this is my first that I have really seen a "car" do that on cruise.

The OB I am sure has its thresholds for ACC engine braking. Again, I like it especially for a road that I am not familiar with and coming into corners going the speed limit provides a degree of safety/caution that I like.

Some folks however may not like the engine braking as it will eat into your fuel economy versus just coasting down the hill and letting gravity take you for a bit. To each their own.
I still find it kind of odd, that when accelerating the CVT acts like a CVT (unless you stomp on it and get into fake shifting mode). But when engine braking it is restricted to the same six ratios that you get with the paddle shifters. This often requires braking, when an in between ratio with engine braking would accomplish the same thing without dragging the brakes. If it has to be this way, then why couldn't they give us 7 or 8 "gears"? All it would cost is a few lines of code.

Engine braking shouldn't eat into fuel economy. If the engine is warm, and you are over 20 mph, then the fuel injectors shut off, and fuel economy is infinite.

I haven't seen any rpm limits, it will crank the rpms up over 4k on a steep hill with a low speed setting.

--Annoyed.
 
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