So, I might be crazy but I swear that the back-end of my 2004 Prius feels looser then it has in the past. We had a really horrible winter storm in Seattle this year and there was a ton of ice on the roads and we ended up getting some pretty nasty ice-ruts. I had to pick up my brother-in-law at the airport the day before Christmas and I got into some of the worst of it. Over all the Prius did fine but there was a lot of sideways motion when I stopped. A couple times the car just slid to the left or right and can to a nasty stop in the bottom of the ruts. There was no traction because I was driving on solid ice. They were some of the most nasty conditions I have ever experienced even after 4 snow filled years of college in NY State and 6 year of off-roading in Jeep Wrangler (previous car). Result, I feel like the Prius has a really loose back-end now. It's hard to say at times because the car has always been sensitive to high cross winds. But the back-end just feels sloppy at higher speeds (60 MPH). It didn't feel this way in the past. The car always felt pretty tight in the past even on the highway. Any idea's. Tires out of alignment? Something getting lose... of frame fatigue? I am bringing in the car for an oil change at the dealer this week and I want to have them look into it. I only have a couple months before my extended warenty is over. What should I make sure that they look at? Our Prius has low miles... about 40K over 4+ years and we take good care of her.
Based on my experience, I would have the alignment checked and pay special attention to the rear toe-in settings. When I first bought my car, the handling was really strange - a check showed that the toe-in was out of spec. Once I got it corrected (with shims) it was much better.
Besides checking the alignment (and struts for wear), get good tires. The Goodyear Integrity tires are poor when new and dangerous as they wear. I have Nokian WR tires (Nokian WRg2 would be the choice now) with 43,000 miles on my 2004 Prius (at 142,500 miles) and they still handle snow/ice just fine. JeffD
Asides tires, I would check, in order 1. Shocks/struts. Worn, they can contribute to dangerous handling 2. Alignment. THe rear torsion beam axle is normally not adjustible, unless you use shims 3. Suspension bushings. You can already have a lot of wear and degradation of the rubber suspension bushings, especially with heavy road salting
