We've got 22k miles on our MY23 and I've noticed something interested as well, specifically about MPG.

When watching the center gauge screen that shows the current MPG, it shows 99mpg (or all the way to the right) when coasting above certain speeds as expected, since it's not using any fuel (or rather since it's just idling the engine while you coast). Try it going downhill and coast, for example, it should show the max MPG.

However, if you use the paddle-shifters to downshift (i.e. engine brake), still coasting, just lowering the gear, the current MPG will start to decline. The more you downshift the more it declines, despite the fact that you are coasting.

I've been able to repeat the behavior. For some reason the Ascent is giving the engine gas even while coasting ONLY while downshifting using the paddles. Basically you will be lowering your MPG if you use paddle shifting to engine brake.

 

@Ceapea what you experienced with the manual shifting is not abnormal. 26.7mpg is actually very good! When I'm driving like an 'old man' to get good fuel economy I usually end up closer to 23mph average, though my commute is part stop & go city and a short time on the interstate.
While it has been discussed here I believe it has been a while since it was last brought up. The short explanation goes something like this: the CVT and engine are operating where they're programmed to be a combination of most efficient and most useful. The turbo really kicks in around 2000rpm so that a sweet spot for power. If the rpm are too low you won't get the boost from the turbo as quick and therefore won't have as much power available for acceleration. Since the CVT doesn't actually have gears, when you switch to manual and 'upshift' you'll usually experience that drop in rpm because the closest ratio to where the CVT was operating is closer to 7th than 8th.
There has also been discussion on using manual mode to increase fuel economy but that's another can of worms. YMMV, literally.

 

I was right at 70 and noticed the rpm’s were at 2k on the dot. A bit high, I thought. So I kicked it into manual and the shift indicator was showing “7.” I kicked it up to 8 and the rpm’s fell about 250, to roughly 1750 or so. So I experimented a bit and every time, when switching from auto to manual at 70, my rpm’s dropped once I went into 8th “gear.” Why? Why would I be cruising in 7th gear and not at the best possible gear ratio? Is this normal? Should I be having a conversation with my dealer? At the time I noticed this, and every other time I tested it, I was traveling on flat level ground.

The answer is "simple", or at least as close as it can be...there is no "gear" when you are not in manual mode. The vehicle electronics constantly change the RPM and transmission ratio to get the most efficient forward motion and that does not always mean a lower RPM. CVTs are different than geared transmissions in that respect because they have the ability to vary the ratio. When you switch to manual mode, the display shows you are in the closest fixed ratio to what it was in fully automatic mode and yes, it's often "7".

 

To be clear, I have never used manual mode until I witnessed the (what I believed to be) too high or rpm’s. I have watched the instantaneous mpg display, and I do understand how downshifting affects mpg. I drove manual transmission cars for over 30 years.
However, I wasn’t leisurely or arbitrarily shifting for the sake of mpg. I only decided to see what was going on, causing the high rpm’s at cruising speed. I will continue to check this out at highway speeds. I cannot see how an effectual 7th gear is at any time more efficient than an effectual 8th gear at 70 mph. Since I discovered this, I have since been able to increase my “city” driving mpg by manually shifting. On a 50 mph road in automatic mode with cruise on, I get to the point where I can manually shift to 8th “gear” and be turning 1300 rpm. I know that this is no place to spend lots of time as there is probably very little usable torque at that speed/rpm/gear combo. One could possibly easily bog down the engine and it is no place for acceleration without downshifting. But just over a very short trip, where my displayed mpg was 16 (over three days of short trip/city driving ) I was able to get it quickly over 19 mpg in that same type of short trip/city driving environment.
One other thing I noticed about mpg on my 22, the computer is a bit conservative. When it shows 26mpg average for example, my math always shows approximately 1.0-1.4 mpg less. I expect that though.

 

To be clear, I have never used manual mode until I witnessed the (what I believed to be) too high or rpm’s. I have watched the instantaneous mpg display, and I do understand how downshifting affects mpg.

how high do you consider too high at 70mph?

I drove manual transmission cars for over 30 years.

I miss my manual transmission cars. Fake manual mode in an auto or cvt just isn't the same

 

I'm a relative new-comer to the Ascent and Subaru CVT's in general. I'm still getting used to them, and I'm still in a learning phase. They do act a lot differently than a traditional automatic transmission, especially in hilly terrain, such as climbing up to the ski areas and mountain passes here in the PacNW. The CVT will maintain a high constant RPM (like 2500-3000) even when letting off the throttle, for a few seconds anyway. After thinking about this odd behavior I've come to the conclusion that it is acting much like a manual transmission would if you were driving the same road. It results in a very smooth driving experience when pulling up a mountain pass with hairpin turns and a constantly changing slope angle. If I were driving the same terrain in a manual transmission, I would tend to keep the transmission in the lower gear and maintain the higher RPM's regardless of the undulations in the hill. This is how the CVT is acting, and I like it. It results in a very smooth driving experience when climbing mountain passes.

 

“how high do you consider too high at 70mph?”


2000 rpm…
At 70 mph, on flat/steady/even ground, with an “8 speed” trans, I would expect around 1500 or even a bit less. This, based on previous 5 speed manual trans vehicles that I have driven.

 

Depending on your pervious motor, you are now in a relatively small motor with turbos so rpms are going to be higher. It is not a 1500 rpm V8.

 

Again, just remember that engine RPM by itself is not as meaningful without understanding what the ratio is as well as the conditions for slope, wind, straight vs a lot of turning, etc. CVT transmission programming take all these things into account.

That said, I generally am able to keep my engine RPM below 2000 most of the time because I've learned to subtly adjust the skinny pedal which can also manipulate the current ratio. I use the instant mileage graphic to help with that. It's the only reason I'm able to get the 17.5 mpg I'm getting in what has turned out to be nearly 100% short trips with a lot of stops "in town". (Highway I typically get 26-27 on long trips)

 

Jim, could you elaborate on what you mean by, and how, you "subtly adjust the skinny pedal which can also manipulate the current ratio". What "skinny pedal", and how do you "adjust" it? Generally, I do not like the feel of the low RPM's that the CVT slides into as I'm driving. While you might say the CVT is producing the best mpg with those low RPM's, I don't like it - almost feels like the engine is 'lugging' - so I usually drive in manual and use the paddles. No doubt I am getting the worst mpg doing this.

 

Since I havent paid it any attention recently and because 70mph is conveniently my normal speed I figured I’d test a couple things for your comparison. All of these behaviors I’d consider normal, having driven my ‘19 Ascent 79k mi since Jul ‘18:

70mph on flat road in D ≈ 1750rpm

70mph on a slight incline in D ≈ 2000rpm

70mph on flat road immediately after tapping the right paddle in D ≈ 1750rpm

70rpm on flat road immediately after moving shift lever to M ≈ 2100rpm

My take on the above is that it’s driving in “8th” on the flats then if the shifter is moved to M it goes down to “7th.”

 

Thanks for that? But so far, in admittedly very limited testing, I always get 2k @ 70 mph. Haven’t been able to get anything less at a steady cruising speed. Only when I manually switch to 8th, will I see 1750 @ 70

 

Are there any open TSBs for your 22? I remember my 21 getting a TSB (I think) applied which had a ECU reprogram applied, which I believe caused a relearn as well. It did slightly improve the MPG, I just don't recall if the RPMs were impacted.

 

When I bought it, it was a CPO car. All recalls and other important maintenance issues were addressed. TSBs, I don’t know about…
Which is why I hinted at contacting the dealer.

 

TSBs are only done if a vehicle is presented with "the problem" that the TSB addresses. They are not like recalls with notifications, etc.

 

My take on this is leave it in drive when you are cruising on a flat road. I put my 2022 in “8th gear“ on a long flat stretch traveling from Kentucky to Ohio and forgot that I had left the vehicle in manual mode. With six people in the vehicle we began to ascend a grade. I applied more and more throttle, not understanding why the vehicle was not responding to my throttle input. When I realized what was going on I shifted back into drive and continued on. The rest of the trip the Ascent had a SIGNIFICANT dead spot in the acceleration. I could reproduce it in drive or shifting through the preset ratios manually. Acceleration drastically slowed when the vehicle got to a set, repeatable “ratio.” I was sure that I had damaged my new vehicle. I stopped several times and cycled the key but the issue did not go away. A few days later when I drove the Ascent again the issue was gone. I feel like I dodged a bullet; my advice is let the Ascent do its thing on the flats, no gas mileage savings is worth damaging the CVT. Use the ratios for steep descents (or curves if you want to pretend it’s a WRX).

 

Why would I be cruising in 7th gear and not at the best possible gear ratio?

The sensors and ECU determine what the highest applicable ratio should be. Forcing a lower gear can cause knock.

it shows 99mpg (or all the way to the right) when coasting above certain speeds as expected, since it's not using any fuel

I believe that when the throttle angle is 0 degrees and coasting that the fuel injectors are shut off. Putting it into manual mode probably overrides that.

On a 50 mph road in automatic mode with cruise on, I get to the point where I can manually shift to 8th “gear” and be turning 1300 rpm.

Wind resistance at 50 is exponentially lower than 70 and the engine doesn't need to deliver as much power and can do that at a lower rpm.

you are now in a relatively small motor with turbos so rpms are going to be higher. It is not a 1500 rpm V8.

Yes!

As the thread progressed, the common understanding that using manual mode for the sole purpose of lowering cruise RPMs isn't necessary or advised. The manual mode is useful for other purposes.