Accelerating in 8th Gear

[RedTailedHawk]

I have a general question for you folks. I just noticed this just yesterday and am wondering if it us normal.

While driving on the highway (~65 mph) I wanted to pass an 18 wheeler that was in front of me. I switched the transmission to manual and proceeded to move to the inside lane to speed up and pass it. I stepped on the accelerator to gain speed (car was in 8th gear) and it would not speed up. The RPMs weren't even increasing and I felt no real power (torque?). I then popped it back to automatic (Smart Mode) and I immediately felt the torque and was able to pass.
As a test, I tried this after shifting to 7th gear and felt the torque and was able to accelerate (in manual mode).
Is this "normal"? I just about had the accelerator to the ground. Now, I was on an incline. But, it worked in 7th gear(?)
Any input from engine and transmission savvy folks is appreciated.
Let me add that I drive a 2022 SXP with 8k miles on it.

 

[bruesjoh04]

I have a general question for you folks. I just noticed this just yesterday and am wondering if it us normal.

While driving on the highway (~65 mph) I wanted to pass an 18 wheeler that was in front of me. I switched the transmission to manual and proceeded to move to the inside lane to speed up and pass it. I stepped on the accelerator to gain speed (car was in 8th gear) and it would not speed up. The RPMs weren't even increasing and I felt no real power (torque?). I then popped it back to automatic (Smart Mode) and I immediately felt the torque and was able to pass.
As a test, I tried this after shifting to 7th gear and felt the torque and was able to accelerate (in manual mode).
Is this "normal"? I just about had the accelerator to the ground. Now, I was on an incline. But, it worked in 7th gear(?)
Any input from engine and transmission savvy folks is appreciated.
Let me add that I drive a 2022 SXP with 8k miles on it.

The problem was you weren’t downshifting. Eighth gear (and seventh as well) are “overdrive” gears where their ratio is less than 1.0:1. You can see the gear ratios for each of the eight gears in the specs here.

The main purpose for the top gears is maintaining speed at a low engine RPM, not accelerating. That’s why if you’re cruising in auto in eighth gear, pushing down on the accelerator will drop at least one, if not two, gears depending on the acceleration requested.

 

[RedTailedHawk]

The problem was you weren’t downshifting. Eighth gear (and seventh as well) are “overdrive” gears where their ratio is less than 1.0:1. You can see the gear ratios for each of the eight gears in the specs here.

The main purpose for the top gears is maintaining speed at a low engine RPM, not accelerating. That’s why if you’re cruising in auto in eighth gear, pushing down on the accelerator will drop at least one, if not two, gears depending on the acceleration requested.

Ah, yes, that makes sense. Thank you @bruesjoh04. I appreciate you laying it out the way you did.