why does my car vibrate so bad

Most likely your alignment needs to be checked. Also, your engine or transmission mounts could be bad, or it could just be a badly balanced wheel. You can diagnose that by looking for unusual wear patterns on the tires.

I own a 1993 Toyota Celica GT. Automatic transmission and I just wanted to let you know that 1993 Toyota Celica's are known to have loud engines and also for their engines to vibrate a lot. If the vibrations are more then normal then more and likely it is something that the previous guy posted. However, I did all of those things and the vibrations still were there. I ended up taking it to a car shop and they found out that my transmission was laying on the sub-frame. This is a common thing for these cars when the transmission gets to be this old.

Mine does the same thing, it's a small car with a pretty powerful engine. It also has like an auto thing to it that keeps the rpms up when idling. Usually if you punch the gas a bit or turn off the ac it stops, but I like to embrace it, keeps the ladies happy ;)

2001 Celica GT-S 6speed manual 90K mi. I had a very bad and loud engine vibration. I replaced the motor mounts and it really helped. I still have a noticeable vibration that makes my keys rattle. I removed and cleaned the IACV (Idle Air Control Valve), that stabilized my idle at 900rpm, however I still have the noticeable cabin vibration (no noises). I'm hearing adjust the valves however I have low mileage. Has anyone solved this issue after the mount and idle solutions?