"Squirming" on highway

Many of us reported slight instability on the freeway soon after purchase, and some not. Compared to most sedans, it does feel that way. Increasing tire pressure "on mine" to 42 psi front and 40 rear did increased stability and mileage, however it has always been more affected by winds, drafts and road conditions more than "our" other vehicles. This is likely due to it's profile, weight and other design factors. This has never been a safety issue "for us" after driving almost two years in everything from snow, ice, rain and sticky hot summers. You just get use to it, like many other things about this car. If you feel unsafe driving one, do not buy it. However if you do buy one, increase the tire pressures as "most" of us do.

 

You are probably feeling the electric power steering which creates a different road feel. It is extremely sensitive and some people have to adjust to it.

 

It is due to the tires and partly the tire inflation. Certain tread patterns will squirm more on grooved roads than others. Inflating past 40 psi will cause the car to pull significantly when it encounters any road crowns, so there is a point of diminishing returns.

Generally speaking, the Prii is a fairly poor highway car as it has poor straight-line stability. Replacing the tires with a set of higher traction tires helped tremendously (as does 17" wheels), but this will noticeably reduce your fuel economy (possibly to TDI levels...).

 

What you call the "squirming" has nothing to do with the actual vehicle but the "feedback" which the car gives you as the driver. You are NOT the first to notice this effect. There is along history with this issue and previous and current Prius models.

In aircraft design nomenclature, this is called "airframe or control flutter." That's why aircraft builders have test pilots. The design and flying characteristics of a vehicle itself might be absolutely stable and performing perfectly, but if it doesn't feel right, the pilot will react to the "flutter" as he or she would to a real situation.

When I took my 2012 Prius"v," I felt an uneasy feeling, like I've felt on a vehicle, when it reaches the threshhold limitation of understeer and goes to oversteer.

After I installed a custom "box beam" center chassis brace that I designed, the flutter that caused this disconcerting "phanton" feedback that mimics loss of control, is gone.

 

The G3 is a small, light, slab-sided car with Electro-Lux "feel-no-evil" steering.
I've got 30,000 miles in type (as of today) and yes....it can feel a little twitchy on the interstate, especially if you're doing the left lane duet with large trucks or in areas with a lot of cross wind.
Still...I drive motorcycles a lot, and it's just a matter of perspective. The G3 is not at all unsafe to drive at any 2-digit speed (given proper conditions) and as others have noted, you just have to get used to the car.
Let's face it. The Prius isn't the most exiting car to drive to the interstate by a long shot, so keeping the car planted firmly in the middle of the road isn't all that challenging, even in high winds and playing in traffic. You don’t have much else to do…
Like I said before.....it's NOTHING like getting batted around on a motorcycle, and after a while you're able to ride on the super-slab without having to think about it.
Numb steering and all...the G3 pretty much goes where you point it, and since it's a front driver the back of the car usually follows along quite nicely.
Not at all dangerous or even very 'squirmy' once you've got some stick time in one.

All things considered equally, it's probably one of the better commuting cars on the planet on the interstate or off, and I would not hesitate to drive one on any road or in any weather that I would drive any other small FWD car on or in. If you get ice on the road? You shouldn't be driving on it until the diggers and fillers put something down to help your tires get a better bite.
Yes.
There are cars on the road that will "do better" in the 20 or so days a year where this type of weather is a factor (maybe) however (comma!) there's no free lunch. You'll pay for that convenience during the other 345 days of the year by buying a lot more gas.
There are many (MANY!!!) irregularities in the Prius driving experience that make several long drives advantageous for anyone wanting to stick one in their garage. Like I said before...ALL things considered, it's one of the best commuting cars on the planet.
There are people who don't have long commutes, have to tow/haul, or just demand that their time in their car be a little different than a Prius can provide.
That's cool.
If there were one BEST car on the planet.....there would probably be.....one car on the planet.
YMMV...
Good Luck!!!
Let us know if you get one, or what you get if you don't.

 

I am interested in posters from North on this issue. Maybe change of tire in winter months? We live in Chicago, so like OP waiting for the "diggers and fillers" to fix the road for bad weather is unlikely.

 

I also find my v3 a little squirmy on the highway, certainly compared to my previous Subaru Outback which was solid as a rock on freeway. But of course, I get double the gas mileage now. My v has the Yokohama tires, in case that has something to do with it.

 

Tires tires tires, (and maybe even tyres). Some squirm on grooves, some don't. The Prius comes with LRR tyres, and perhaps they give that feeling. I've never had any problems with the Prius handling, and certainly not in winter (using Nokian WR and WRGII). It's more stable than my FJ Cruiser on ice! Deep snow, now that's another matter entirely.

A set of proper winter tyres will cost you around $500 to $600 including wheels. If you slide into someone because you are running summer tyres (or off the road) good luck getting away with less than that much damage. You do the math. Do you need winter tyres?

 

I vote for the LRR types too and the chassis. Add snow tires and a front brace, and that feeling will disappear. Probably just using standard tires would help too but you will lose in the FE department.

 

Toyota recognized the "flex" issue in the center exhaust system tunnel and now supplies all Prius models with a "stiffer" mid-chassis brace. Those of you, who have installed mine know that it is even stiffer, but not in the way that the original BT Plate or its clones worked. Toyota recognized that the brace must have rotational flex or twist to allow the right side and left sife of the car to move independently. Not doing so would eventually rack the mountings and ultimately cause metal fatigue.

Mine is a stiffer verson of Toyota's but uses an innovative lighter weight one piece design to achieve what Toyota did with 5 pieces of steel and 7 welds. Mine is one piece and has no welds.

 

lots of good info here. this problem can be easily fixed be it mental or physical. i have mike's center brace (+ tanabe stb, rsb) and it vastly improves the handling. Furthermore, the prius comes with the oem yoko s33d tires that are notorious for tramlining. A couple of users here immediately traded them in for different tires; they experienced immediate improvements.

 

After installing Rude person's's front brace I noticed a very segnificant improvment in straightline stability.
I have the stock 2012 mid brace and Yoko S33D tires.

 

I wonder if the "squirming" you are talking about is the same that I experienced. I drove from Texas to Mississippi to visit the in-laws and while going over a bridge in Biloxi, the whole car was squirming. I attributed it to the bridge being metal in the middle(one that opens to let larger ships through) and the tires? I have 17inch Michelin Primacy MXM4's. I couldnt pinpoint the issue but my only thought was that the tires are either too narrow or the tread made the car squirm? I haven't had that same squirming anywhere else except that bridge.

 

Yes, metal grates like will definitely make most cars do this.

 

I have noticed the same thing. I figure it is interaction of tires and grooves, just like your salesman said. It is not actually doing anything. The car still responds immediately to small control inputs. It's just a training matter. I just wait it out, and the car keeps going straight.

 

The correct term for this condition is Tram-lining.

 

I live in Maine and have a Prius III since march 2010. My daily commute is 130 mi R/T in any weather: snow, ice, rain - you name it. No problem at all. I replaced stock tires after they were worn out to Hankook Optimo 727. Both sets of tires performed well. Before Prius I had Camrys for 17 years on the same route. I should admit: Prius is pretty sensitive to stronger side winds compared to Camry but nothing dramatic or dangerous in my view. I feel pretty safe in a Prius, but this is subjective, of course. LOVE THE GAS SAVINGS BIG TIME!!!! PRICELESS!