I've had my NX350 with 8 speed automatic transmission for a few weeks. I've found that if I take my foot off the gas at around 40 mph, sometimes (not always) the car will dramatically downshift. By that I mean, it's as if some ghost had stepped on the brake pedal. So, I will go from 40 to 30 in just a couple of seconds, accompanied by a feeling of alarm that somehow the car was braking for some reason. (That's in contrast to what I would expect when taking foot off the gas, which is a gradual loss of acceleration and accompanying downshifting.)

Is this a known issue? It's not a case of collision avoidance -- it happens when there is no car in front of me.

 

Hmmmm.... brakes hanging up,? Have you checked to see if they are dragging? I dont have your model, can you see if the car is actually downshifting to a much lower gear? May wanna consult w Lexus very soon.

 

I'd guess it might be proactive driving assist. I'd try turning it off in the driver assist settings in the center screen.

 

Unfortunately, this is just the nature of the 8 speed automatic transmission. It's always trying to downshift when your foot is off the pedal. My 2023 behaves the same way.

 

Do you have the NX turbo, and what was your previous car and engine? You may not be used to the engine braking effect of the turbo-4 in the NX.
While not an NX, my previous car was the IS Turbo, and before that that I a Big American V8 Luxo-Barge. It took me some time getting used to the IS's high compression 4-cylinder engine, after luxuriating in a V8 tuned for smoothness.

 

+1 on this.

The transmission is always very proactive keeping the best selected gear for quick & responsive acceleration when coasting which does induce more engine braking generally. The only exception is coasting down to 1 to 2 mph it will hold onto 2nd gear almost to a stop and does have a bit of lag if you stomp on it without a complete stop sometimes. Often I've seen it accelerate from almost a dead stop in 2nd. Toyota has generally had more than its fair share of transmission programming that take its sweet time finding a gear before accelerating after coasting, so with this implementation, I approve.

 

+1 aarongue6

I would check to make sure your proactive drive assist is off to rule it out.

 

Take it to the dealer, that is not normal-----------------------that's one problem I've never had.

 

Obviously, the first thing you did was take the car back to the dealer. What did the dealer say and how did they fix the problem assuming they determined there was a problem ?

Good Luck

YMMV,
MidCow3

 

Several posters have suggested I take the car to the dealer. But in my many years of dealing with repair shops, I've found that intermittent problems pose a challenge. I can spend hours taking a car in and leaving it or waiting for it ... and if the intermittent problem doesn't happen, the response is "it performed fine for us." So, when possible I wait until an intermittent problem becomes regular and/or predictable. So no, the dealer hasn't seen it yet. That's kind of why I posted here, because I've often found forums to be a help when there's a known issue.