[FUNFER2]

As already said, in such a short wheelbase and light weight, the alignment and balancing is extremely,.....important !

Take the car to a reputable,..... shop that has a "Hunter" machine. It makes a huge difference. I can drive at 100 mph + with no shake.

Some cars, even Cadillac, have what's called "Harmonics", where the engine & drivetrain are at a imbalance, creating this affect. Some manufactures like Lexus to Ferrari's, add weight to the chassis to lower the harmonics or even stop it altogether. I have my harmonics at around 63 mph, so I'll slow down or increase speed.

I do not like a rubber vibration joint in the steering shaft, as I like to feel the road beneath me. Same goes for power steering & brakes. Some people like them, some don't. A light weight car can get twitchy and can possibly,...... loose control.