It's possible that the wheels are out of balance, I'd have a trusted tire shop look into that.

Actually those cars are pretty good for non enthusiasts, and while I personally don't care for fwd automobiles, this model and year of Buick makes for very good transportation on American roads for a reliable "drive it and forget about it" car for non enthusiasts.

I'd keep it, I think it is a very low cost (dollar per mile) car to run, though if it has significant rust or repaired collision damage, I'd forget about it.

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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)