I've posted about this before but I have new data that sheds new light on the problem.

So I got my car in May, and when
Going 120-140 Km/hr I felt severe vibrations (on Hwy 400) - it made my arms sore.
So the first time I brought it into the dealer they did a wheel balance and the car felt exactly the same. The second time they did a wheel alignment. I still felt vibrations a bit, but it did not get incrementally worse as I was accelerating from 120-140. Then this weekend, the car felt great. Remind you, it was quite hot. So I thought everything was alright.

Then this morning, it was cold, and I felt significant vibrations but at 80-100 Km/hr.

Obviously the temp change had something to do with it. The question is, is it the tires or some part of the car?

Please lend me your wisdom.

 

"So the first time I brought it into the dealer they did a wheel balance and the car felt exactly the same. "

The same as before the vibration, or the same as when you took it to them? My guess is that you have a bent wheel and the tire pressure change as a result of the temp change masks a little or worsens the vibration. An alloy wheel can bend pretty easily.

 

I noticed the exact same thing on my '01 ES this morning, never noticed it before, but it was vibrating like crazy today on the 401, and it was really quite cold this morning.