[PriusPrism]

Hi..got my daughter a 2018 w. 11K miles at a Lexus used car lot. The car drove fine on test, but now, in 2nd day around a 25 mi. radius on hwy., it would intermittently develop a low vibrational rumble-nothing shaking in the car, but noticeable by all. It seemed to come and go, not triggered by road surfaces, throttle position etc-afaict.
We have a 90 day lemon law if it has to be repaired more than 3x=refund/return. I also have to have the car inspected, so will go to a Toyota dealer tomorrow am or asap!
My fear is this is some sort of intermittent (came and went a few times, lasted about 1min or so) driveline or transmission issue-unless tell me how an a/c on continually at 71 in a 92f day would be this noticeable?
What are possible things to have them check, given the dufuses at Toyo service probably don't take them on highway jaunts, at least on first visit? I'm doubtful that road rash or tire/balance issues would come and go so quickly....but again, it seems to fade when we drive uner 60 or over 70!!!?
I don't think there are major accidents w. this car's history, but iit does look like the rear bumper cover may have been replaced-oh oh!
Help appreciated immensely!!!

 

[Easy Rider]

Impossible to diagnose something like that by "remote control". You have to be there.
It could even be something perfectly normal.......like the gas engine starting and stopping.
A hybrid does that you know !?!?

And you really should mention that it is a Prime model because they work a little differently with a bigger battery, causing the gas engine to stay OFF longer if the battery is charged up.

 

[PriusPrism]

NO..I HAD NO IDEA gas engine started/stopped while doing 60mph on hwy flat road...I thought it was a Tesla without the poor quality.
This is a steady state, no brakes regenerating (though I wish there was an icon when I engage that separate system-without killing myself or car behind me), no gas pedal burying wide speed varying ride where you can go about 10 mi at 61-70. a/c on or off, cruise control on or off, lights on or off. SOMETHING parasitic this way comes AND GOES, and I've done nothing to provoke it. I had two riders who noticed how the car had a sudden, rumbly vibration, mostly through the seat/floor/chassis. While we know our other car, a RAV4 2022 Hybrid, isn't QUITE THE SAME.....you are right, you gotta be there-and good luck w. getting a service mgr. to take a 12 mile hwy. rida and hope it comes up.
The Prius Prime is a 3 year old car w. 11K miles, and it runs extremely smoothly (if a little louder in road noise isolation limits), but this....well, it just suddenly turns from butter to econobox slogger, as it a "cheap ride" automatic damper came on for those missing their Prius C.. The steering doesn't shimmy, the road has no apparent change in material or condition and it goes away...soo who cares? Well, we do, as the Prime is a little bit of "movin on up" and the beans ain't supposed to burn on the pan or Prius suddenly fry on the grille...it is too nice a ride in action not to notice when it goes a bit choppy sloppy, Jeckyll and Prius?

 

[Easy Rider]

NO..I HAD NO IDEA gas engine started/stopped while doing 60mph on hwy flat road...I thought it was a Tesla without the poor quality.

OK.....so maybe it is not the engine itself but probably is related.

The larger battery in the Prime is good for.....what.....25 miles if fully charged ?
And if you do that distance at fairly slow speed, the gas engine might never come on.......right ??
REALLY quiet.

BUT then if you need more power than the battery itself can safely give, the gas engine cuts on and then off later.
Like going up a small hill at 60 MPH for instance.

So that's when your loose motor mount or exhaust leak shows up.
Have you looked lately to be sure you still have a catalytic converter in place ??

Somewhat interesting discussion but eventually you really need to have it inspected.
You might start by NOT charging it for a couple of days so it runs close to the "conventional hybrid" mode to see if it acts any differently.

 

[2015 V Driver]

Hi..got my daughter a 2018 w. 11K miles at a Lexus used car lot. The car drove fine on test, but now, in 2nd day around a 25 mi. radius on hwy., it would intermittently develop a low vibrational rumble-nothing shaking in the car, but noticeable by all. It seemed to come and go, not triggered by road surfaces, throttle position etc-afaict.
We have a 90 day lemon law if it has to be repaired more than 3x=refund/return. I also have to have the car inspected, so will go to a Toyota dealer tomorrow am or asap!
My fear is this is some sort of intermittent (came and went a few times, lasted about 1min or so) driveline or transmission issue-unless tell me how an a/c on continually at 71 in a 92f day would be this noticeable?
What are possible things to have them check, given the dufuses at Toyo service probably don't take them on highway jaunts, at least on first visit? I'm doubtful that road rash or tire/balance issues would come and go so quickly....but again, it seems to fade when we drive uner 60 or over 70!!!?
I don't think there are major accidents w. this car's history, but iit does look like the rear bumper cover may have been replaced-oh oh!
Help appreciated immensely!!!

Like others, I'd rather hear/feel before diagnosis. Given what you have told us, one possibility is the front suspension. Good luck with the Prius, it is certainly worth it.