I use the adaptive cruise control (ACC) feature on my 2022 Mitsubishi Outlander every time I get in the car. It's a great feature that allows you to hold your speed relative to the traffic in front of you. It holds your position by speeding up or slowing down even fully applying the brakes if the car in front of you decelerates rapidly. Old fools down here come almost to a complete stop with little notice in making a turn.

Imagine my surprise at my 16,000 mile service yesterday that the rear brakes were worn to the point of nearly touching the rotors. Front brakes very little wear other than normal for 16k miles. Apparently it uses the rear brakes to maintain the speed when the vehicle in front of you is slower than you have it set. Live and learn.

Not the first time I've seen this mentioned.

I believe a lot of auto brake hold features use the rear brakes as well.

That does not seem right, but what do I know?

I had 63k on my Outback (in 5 years) before I had the rear brakes and rotors changed, and I use ACC all the time. But I am rarely in heavy stop-and-go traffic. Normally, my engine is slowing me down in regular traffic. I have lights that show me when the brakes are applied, and I do not see those lights very often.

Front brakes are probably due now at about 75k.

My 2018 Yukon has adaptive cruise and is on original brakes at 90,000 miles.

My first Outback needed the rear brakes replaced at what I considered a "low" mileage when the front brakes were fine.
Couldn't figure out why until now.
I use the adaptive cruise control all of the time like nosticks and that Outback was in traffic all of the time.

Good to know. Thanks for sharing.

I keep mine shut off unless I am on a long interstate highway trip.
Be pretty hard to use it here in town for just running errands.

I used it a lot in my Explorer when I first got it.
It has 'Intelligent' ACC, where it auto-adjusts the set speed based on the posted speed limit.

Issue for my commute, is that the HOV between the mainlanes drops to 45mph in 2 places, and the system grabs that & starts decelerating (luckily without tossing out an anchor).

Now, I only really use it for longer trips.

It makes sense, because with automatic transmissions having the top two or three gears as overdrives (gear ratio of less than 1:1), just letting off the throttle may not slow the car down enough.

quote:

I use the adaptive cruise control all of the time like nosticks and that Outback was in traffic all of the time.

What kind of traffic are we talking about? Adaptive or not, cruise control is not appropriate for heavy and unpredictable traffic.

I have 2 Subaru’s with ACC. Never noticed this so I can’t say. Here’s what I can say, my wife’s Toyota also has ACC, an older version. It is noticeably rougher and more prone to brake applications in use. The Subaru system is almost gentle in use. So gentle in fact that I would guess it relies on engine braking/throttle more so than brakes. If an obstacle pops up it has been more aggressive. Bottom line I think some systems are better than others. 16k seems like a joke. That is awful.

I like to save gas in my ‘20 Crosstrek, so I rarely use cruise. Let’s say I use cruise for 65 mph. The tach reads higher while using cruise than when I’m manually staying at 65. And for those few times I do use cruise, I instantly turn off ACC because it will keep me stuck behind someone slower than me when my mind is on something else, not realizing it at the time. I also don’t like the ‘feel’ of ACC slowing me down, and now that I know that it is because of the rear brakes, I will definitely not use it again.

Also, I was driving up a relatively steep deep snow covered dirt road, and I wanted to test out my Crosstrek’s special traction mode. I only ascended, and after about a mile or two, we stopped for pictures. When I exited, there was a heavy odor of brake use. I stopped using that special mode after that because I really didn’t see a difference between standard and the special X-Mode. My Crosstrek ate snow and ice in really tough Colorado high country during a winter storm without fancy schmancy traction modes…like a BOSS!

With the low mileage would this be covered under warranty?

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Originally posted by PR64:
With the low mileage would this be covered under warranty?

IIRC, in most cases, brakes are considered a consumable, and not typically covered under a standard warranty.
An Ext Warranty might, though.

Cruise controls are great for, say, I-40 between Tucumcari, NM and Amarillo, TX. The terrain is flat and relatively lightly traveled. I-40 through Tennessee is a different story. It is hilly, curvy, heavily trafficked and there is a great deal of speed differential between the slower and faster drivers. An underpowered car will rev high and downshift two gears to climb some grades.

There is a pretty marked difference between my 2020 Explorer & my wife's 2018 Expedition, as far as ACC is concerned.

The Expedition is much quicker to get on the brakes when a car moves into the radar range, where the Explorer will coast a bit more before applying the brakes.

They both are fairly conservative with acceleration, in normal driving modes, and I actually like the ACC in the Expedition in tow/haul mode, as it extends the follow distance a bit more than the 'normal'/default mode.

300hp & a 10spd automatic, the Explorer manages speed changes well. Doesn't need revving to the moon to adapt to speed changes or inclines (As much as there are in SETX).

At 16K? That seems excessive (to me).

I recently replaced pads on a 2019 Highlander that has adaptive cruise control. The rear pads were worn a little more than the front. That one had about 75K on it at the time and I was thinking that was a little early but not horrible.

It depends on your commute. As others said, long flat, and straight stretches of road with steady speed is the optimal environment for cruise control.

I find that cruise control doesn’t know how to “coast.” It’s either gas or brake. Slight short incline? The computer doesn’t know it’s short; it just knows the speed is going down so it applies gas. Past the crest of that short incline? It doesn’t coast and let friction slow the car down, it applies the brakes to slow down.

For adaptive cruising, car ahead is slowing down? It brakes instead of coasting. Car ahead speeds up? It accelerates at a faster rate than if you were driving manually.

I use the ACC on my wife’s Explorer to get the lane keeping/centering. For whatever reason, it seems the lane keeping/centering function only works when the ACC is on and set. I’ll set the ACC 10 or 15mph lower than the speed limit then just drive my normal speed.

quote:

Originally posted by trapper189:
I use the ACC on my wife’s Explorer to get the lane keeping/centering. For whatever reason, it seems the lane keeping/centering function only works when the ACC is on and set. I’ll set the ACC 10 or 15mph lower than the speed limit then just drive my normal speed.

If it's a 2020+, the lane departure should function without the cruise active, but the lane centering requires cruise active.
Centering works pretty well in my 2020 Limited, the departure just vibrates the steering wheel if you're riding the lines. But, I have mine [departure] set to low assist IIRC.

One of the reasons I won't use adaptive cruise is for that reason. The last thing I want are brakes being applied to hold me back most every time I drive down a hill. Hills are basically all we have here (you're either going up or down.) The brakes on my sister's Subaru Crosstrek needed replaced at 19K and she was furious. The dealer told her that's pretty common now with cruise that brakes to hold speed going down hills.

Another reason I don't want it is I may look down to see I'm going 68 mph a ways back from the car ahead, when my cruise was set at 75mph. It gradually slowed me down to pace the vehicle ahead where with regular cruise, without even monitoring the speedometer, as I got closer I'd just pull to the passing lane and go past at 75 mph. I'm sure adaptive works for many people who drive in a lot of traffic and on flat or rolling terrain, not for me though. Fortunately if I press the cruise button and hold it, it cycles from off to adaptive, to conventional cruise.