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2021 Ascent Premier
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Discussion Starter · #1 ·
Having spent a lot of time gleaning information from this forum, I want to contribute from our experience with Ascent Premier (Canada - so top trim with tow package) and dealer installed OEM hitch; Blizzak DM-V2 245/60R18 at 35psi for this winter time drive; Tekonsha Prodigy P2 brake controller.

I initially had WDH and I know this has the potential to draw fire, but I have my fire retardant system on full and do not intend to be baited; I just want to share information below that hopefully will be helpful.

Trailer - Airstream Caravel 16RB, upgraded to Michelin Defender LTX 235/75R15 (M+S rating) at 45 psi; curb weight 3434 lb (from plate, not brochure), GVWR 4300

I did some weights on CAT Scales, but the only way for the 3 axles to fit was by having the front axle the the trailer axle right on the edge of the plates. The trailer weight was only 2920 lbs (without WDH), 2 propane tanks and 2 lithium batteries so I am suspicious of the weights.

First trip was about 1350 km return, Ontario highway 401 (divided, multilane). WDH was used for whole trip. The outbound was without the antisway bar. Towing was fine with no sway issues despite some moderate cross winds and lots of transport truck traffic. On the return I attached the antisway bar to see if it made a difference. It did - felt much worse with a very light feeling front end. I took it off at the first chance. I think it magnified any trailer movements since all forces are met by an equal and opposite reaction. I never was convinced it was needed for the Ascent based on the electronic antisway system, but wanted to see for myself. Average speed for the trip was 85 kph (53 mph - if you are not Canadian, you will learn some metric) and fuel consumption was 20 liters / 100 km (11.8 mpg).

Second trip was just completed - We travelled 4770 km from Ontario to British Columbia over 8 days with a mix of multilane and 2 way highways, temps around freezing to -15C (5F), fresh snow, packed snow and ice at times. And some mountains. We had lots of stuff in the Ascent, the trailer had empty water tanks, not much cargo. While driving slowly through one town on our 3rd day, a railroad crossing sheared the bolt holding the chain from one of the WDH bars and that was the end of using them. I shifted weight in the Ascent forward by putting the heaviest stuff on the middle row and 4 jugs of windshield fluid went to the back of the trailer. All the winter weather came after this, and I never felt any issues with the trailer, driving at appropriate speeds for the conditions. I had to do one aggressive stop on packed snow, downhill grade due to some construction and although it took longer, the ABS worked and the trailer stayed directly behind me. I often looked to make sure I was still towing because if felt so smooth! Once, on dry pavement with cruise control on and I must have been distracted as the cruise deactivated, alarms sounded (think airplane disaster scenes!) and the trailer swayed a couple of times before everything settled down. I guess that is the trailer stability system at work ;). Crosswinds were not a problem but could certainly be felt. If I missed a transport truck coming up from behind, I would feel it as it came even to the trailer, like a bow wave. It felt a bit like being sucked in, but easily corrected. Pulling up inclines was fine; if particularly steep, I would try to limit to about 3500rpm for gas economy and I just felt that was a reasonable limit to not overstress the engine and CVT. Our fuel consumption was similar to the 1st trip 20.2 l/100km for the whole trip. The mountainous sections were surprisingly about the same, probably because speed was reduced for the conditions.

If I had started this adventure in the summer, and if we had more time between getting the trailer and making this trip, I would have tried to check the weights, including tongue weight, more completely. Something for next spring when we plan on making the return trip. It was somewhat ambitious to embark on this trip as we were also getting to know the trailer. If anyone is interested - it was very cozy with the propane furnace :). Next up - reviewing this forum for best way to wire a DC-DC charger as running out of battery was our one concern. We have 2 Volthium Lithium 100Ah which have internal heaters to allow charging at sub-freezing temps. The 7-pin connector could only do 4-5A so I used the 110V outlet in the car (100W capacity) and an 8A charger to charge one battery while driving; swapping batteries in the cold was not fun however. Oh ... and also recommendations for a new hitch that doesn't weigh 100 pounds (if anyone wants to buy a Eze Lift WDH system; please message me :) ).
 

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I initially had WDH and I know this has the potential to draw fire, but I have my fire retardant system on full and do not intend to be baited; I just want to share information below that hopefully will be helpful.
You're going to give @Robert.Mauro heart palpitations.

Great write-up.

Obligatory "unibody vs. frame on rail" discussion.
 

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2020 Ascent Touring
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I did some weights on CAT Scales, but the only way for the 3 axles to fit was by having the front axle the the trailer axle right on the edge of the plates. The trailer weight was only 2920 lbs (without WDH), 2 propane tanks and 2 lithium batteries so I am suspicious of the weights.
My only weighing experience is with my SUV and utility trailer at the landfill. Their scales are state certified but under 5000#s they don't even register. They just wave me through and charge the minimum. Maybe there's a nearby RV scale or keep your eye out for a RV weighing event.
 

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2019 Ascent Touring (CWP)
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Per the manual, one should never be used, probably because our vehicles are unibody.
Small correction to that...it's because OUR unibody isn't designed to support a WDH. That's not universal. Grand Cherokee, for example, has been unibody "nearly forever" and requires a WDH when the tongue weight exceeds a particular amount. (about 50% of total capacity limit) Subaru didn't design Ascent to support the leverage that WDH uses so that risks damage. Hence, they prohibit it.
 

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2019 Subaru Ascent Limited 2010 Subaru Legacy GT limited
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I would try to get an accurate weight of the trailer or at least the tongue. I like to have my tongue weight around 10% but it may be prudent to get that up on a trailer you have experienced sway in. The ascent will squat some with the added weight, but your drive will go much better, and you will hopefully never see those flashing lights and beeps again.

Great write up of your experience and nice to see an airstream that works with the ascent. Sometimes on long drives I wish our trailer had rounded edges, lol.
 

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You should not tow with cruise control. As I understand cruise will not activate the trailer brakes. Also when I tried cruise the engine rpms went up 500 rpm and the instant gas mileage went down. So even if you could use cruise it would be less efficient towing.
 

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As I understand cruise will not activate the trailer brakes.
If ACC applies the Ascent's brakes, the same signals are present to accurate the trailer brakes. But I absolutely agree that when towing, one should not use cruise control. Towing is a "hands on, foots on" operation.
 

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As I understand cruise will not activate the trailer brakes
If ACC is just letting up on the throttle, the trailer brakes aren't applied, just like lifting your foot of the gas pedal. If ACC is applying the brakes, the trailer brakes controller will be activated. The little icon on the dash has the brake lights on when ACC is using the brakes.
 

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You should not tow with cruise control. As I understand cruise will not activate the trailer brakes. Also when I tried cruise the engine rpms went up 500 rpm and the instant gas mileage went down. So even if you could use cruise it would be less efficient towing.
I think this advice is antiquated. I use cruise when I'm towing long distances, and that doesn't mean my foot isn't at the ready. There's no logical reason not to use it, as your foot can remain on the throttle pedal if you feel it necessary.

Cruise or no cruise, driver attentiveness is what matters. And the brakes work just fine, coasting down to speed without ACC also doesn't apply the trailer brakes, so I'm not sure what that point was meant to highlight.
 

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I think this advice is antiquated. I use cruise when I'm towing long distances, and that doesn't mean my foot isn't at the ready. There's no logical reason not to use it, as your foot can remain on the throttle pedal if you feel it necessary
It's recommended to not use by Subaru because ACC uses engine braking quite a bit. That, of course, isn't a good idea for braking a trailer, for a few reasons.

That doesn't mean I don't use ACC when towing, but it does mean that I make sure I personally take over all braking whenever the vehicle needs to be slowed down, whether from a hill or traffic flow. In other words, I only use it (some of the time) on flat, open, roads.
 

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2022 Ascent Onyx, Ice Silver
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It's recommended to not use by Subaru because ACC uses engine braking quite a bit. That, of course, isn't a good idea for braking a trailer, for a few reasons.
Diesel pickups with exhaust brakes use engine braking extensively when towing, it really saves the service brakes. The manuals do caution to not use it on icy/snowy/slick roads, otherwise, it is pretty common practice. I am curious as to why Subaru advises against it. Perhaps due to the CVT transmission?

That brings up another question....do most folks use the manual mode on the CVT when towing? I've had trucks with both automatic and manual transmissions. I find that manually selecting gears when towing often gives a better match to the terrain, engine RPM, etc than leaving the selection up to the TCU. This is the first CVT I've owned, so it's all new to me.
 

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I am curious as to why Subaru advises against it. Perhaps due to the CVT transmission?
From an operation and testing perspective, there's no added stress on the CVT from engine braking, but there is added stress on the engine. Alas, a gasoline powered 4 cylinder's requirements will be different than a diesel's.

do most folks use the manual mode on the CVT when towing?
The manual suggests using manual mode when necessary, though with the current TCM logic, I haven't needed to.
 

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I've not noticed any significant engine braking unless I manually downshift the cvt myself. Am I missing some point here, acc coasting down a few mph is the same as me letting off the pedal to achieve the same result. I've yet to have acc induce a downshift to slow down, especially towing.
 

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I've tried using manual mode for towing, and I kept forgetting to downshift...I was able to cruise at a lower rpm but at what cost to the powertrain. So now I just let the computer do its thing.
True, lugging is hard on a petrol turbo 4 Cyl engine. Doesn't the AI tell you "downshift, dummy!!"? o_O
 

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Discussion Starter · #18 · (Edited)
My knowledge of cruise control is that it improves fuel economy. As mentioned by others, driver attentiveness and adjusting to the conditions are both primary importance whether towing or not. With good conditions (dry pavement, moderate or flat terrain, etc), I found that ACC worked well. Going over mountain passes and driving snow covered roads, there was no way I would use it. I never noticed an increase in rpm when engaging it. It does use the engine to control speed on descents, but anything excessive activates the brakes and I never experienced sway. I did have lane assist turned off, based on other posts on this forum and it did seem better that way. My thumb was always over the CC switch and right foot in place. Overall, with several long days of driving I found it less tiring. The towing was so smooth that I often wondered if the trailer was still there, so having the ACC kept my speed from creeping up! And I think maintaining constant speed is courteous to other drivers, especially on two-way roads.

As for the CVT, that is one issue that I have read in places may be a weak spot. Not sure why. I did notice a slight burning smell a couple of times after stopping for fuel. Engine oil was fine, engine and oil temp were also OK. I wondered if it was the transmission; despite the transmission oil cooler in this model, could that be the source? I do not believe there is a gauge or warning light for this.
 

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I've tried using manual mode for towing, and I kept forgetting to downshift...I was able to cruise at a lower rpm but at what cost to the powertrain. So now I just let the computer do its thing.
That too was my issue/concern. If I don't have that third pedal, I'm horrible with manually shifting. Oddest thing.
 

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My knowledge of cruise control is that it improves fuel economy.
  • Ascent Cruise Control improves fuel economy in many (but not all) situations.
  • Ascent Adaptive Cruise Control only improves economy for those who don't/won't/can't moderate the gas pedal decently.
  • Ascent Advanced Adaptive Cruise Control (2021+) only improves economy for those who don't/won't/can't moderate the gas pedal decently.
The reasoning is simple. ACC and AACC both increase and decrease speed with traffic. Speeding up the Ascent repeatedly will eat gas.

Except for using "ECO" mode on ACC/AACC, a human who's moderating the throttle better to accomplish more fuel efficient accelerations will generally beat the computer, since all its doing is working on closing a gap in traffic at whatever "follow threshold" the user has picked. There's a lot of inertia to overcome every time the Ascent's speed is dropped 20 miles per hour and the human or car needs to speed it back up.

I have never tried beating it vs ECO mode (too slow for NYC Metro Area traffic), but I can beat its fuel economy for all other ACC/AACC modes.
 
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