Bad Experience!!

Is this your first Prius? For efficiency, hybrids tend to have less toe in on the alignment. This could lead to some unstablity at higher speeds. Then some roads and pavement could also cause it. I've notice such behavior more on concrete with the parallel grooving.

 

Then you can rule out this being from Prius quirks.
Guess you'll need to try another dealer. Some just suck, no matter the brand.

 

From what I have read, diagnostic fees are not covered by the warranty. Out of goodwill, to keep the customer happy many dealers eat this cost even if the warranty repair is not made. This is more true if you have purchased the car that dealer and have a good relationship with the dealer. But in your case, this did not apply. Being able to reproduce the problem at the dealer visit is the minimum requirement for warranty coverage, but you may have better luck with the dealer where you bought your car. Good luck.

 

have you checked tires pressure? some have had to replace oem tires

 

+1 on tire pressure. It you're running very high tire pressure, you can get the effect you're describing.

 

+2 on tire pressure. New car was the clue. They ship with extremely high tire pressure and dealers often forget to correct that before turning it over to the buyer. If they missed that, they may have missed other dealer prep items as well.

 

How fast were you going on the highway? Does this instability happen when you are driving straight or only when you are trying to maneuver? Any prevailing wind?

 

I have not driven my 2020 PRIME on highway yet due to COVID-19, but for my 2017 PRIME, I had no problem with highway driving up to 90mph. Anything above that speed, I feel unsafe in any car. LOL In any case, I don't think I have felt any instability in my PRIME at any speed I have driven. Yeah, if you are experiencing this instability issue and you can reproduce it, I would contact Toyota customer center and open a case directly with them. A most likely scenario, they will send an engineer to check your car at a dealer. I had my 2017 PRIME checked out for the rust problem on the rear hatch handle. They kept the car for a week and in the end, just paint it over the rusted area. I was not very happy with the result but did not cost me anything. Toyota provided me with a loner Prius (not PRIME) during this time, but this was all at the dealer I purchased the car.

 

Leon, can you make a video that shows the problem? If the shot shows you holding the steering wheel steady and shows the view to the front with the car wandering on the road, that would be great to show a service manager. If it shows you moving the steering wheel correcting the swerving, that won't look good...which came first, the swerve or the wheel movement, they'll say.

Did they give you any paperwork showing what they inspected? Did they check the wheel alignment and give you a print out of the current settings? Even if the current alignment settings are "in spec," sometimes the spec is so wide that one side can be at one extreme in spec, the other side of the car at the opposite extreme in spec, the alignment is terrible, and the car drives poorly.

If the cold tire inflation pressures match the placard on the driver's door jam, then I think you have a misalignment or a bent suspension part. And, they'll claim that you hit something to cause the problem...be ready for that. Always be sure the work order describes the problem. No cure, no pay. A video that clearly shows the problem is a big help showing that the problem is real. First...find a piece of road near the dealership where the swerving happens. This is where you want them to experience the problem. Also be aware of tramlining. This is where grooves in the pavement cause certain tires to wander. While you'd expect Toyota to put on tires with little tramlining action, but this isn't something the dealership can help you with.

And, consider getting an independent alignment shop to check your car. It may be less frustration and certainly less cost. They can align it to the center of the spec, where you want it, and they can look for bent or defective parts.

About the service writer and the service manager...the service writer is a commission salesman. No charge to you, no income for him. The service manager is the boss of the department, usually doesn't meet customers, but he's the boss when you need one.

 

interesting case. could be that section of road's HARMONICS somehow matches your car's tires, etc. Had an old 1968 Dodge Van that was OK at 100mph but on this one turn at about 35mph would shake and shudder like mad.

How does it do on other roads?

 

Did they do a wheel alignment?

 

This is one of those instances where it's probably worth it driving to the dealer where you purchased it as they'll most likely give you better service.

 

Or any other dealer.