Mysterious shaking

Hello, I have a 2000 Volvo S80 T6. I have been putting in premium gasoline ever since I got it about 5 months ago. The previous owner did the same. I called my mechanic and asked about regular gas vs premium gas. He said regular gas would do just fine. So about 4 days ago I took my car to a parking lot and had some fun in the snow. It was mainly just pulling the e-brake around corners. I hit a few snowbanks, but no visible damage to the car. Anyway, I was below a quarter of a tank (21 gal) and I filled it with regular. I drove it straight home after that less than a mile away. Now when I drive it above 40mph the entire car vibrates as a vibrating chair does. It is almost a shaking, even. At first I thought it was because of the gas, but after talking to friends, they think it could be an allignment issue due to my parking lot activities. I also just had to replace the transmission and brake lines about a month ago. What do you think is the cause and the actual problem with my car? Is it an expensive fix, or if I like the new vibrating chair feature I could just leave it? Thank You!!

I think your friends are right. Take it to a local alignment/suspension shop for an inspection.

If its remained cold where you are, you may have just ended up with chunks of ice stuck up in your wheels or elsewhere.

If the weather has remained cold, there may be ice stuck in the wheels, throwing them out of balance. You could have packed some snow in there while sliding around, and it may still be frozen in there.

If you really whacked a snow bank hard, alignment problems are a possibility.

I disagree with your mechanic’s advice about running regular in this car. This engine is turbo-charged, right? I recommend using the fuel specified in the owner’s manual.

I believe it was a chunk of snow in the tire, as it is over 34 degrees now and everything is melting and I have not had the problem anymore. You seem to be correct! And yes it is turbocharged, but i do not now much about what the type of gas will do… I will have to refer to my manual. Thank you both!