The GNX is GODDLY!!!
0-60 in 4.6 seconds... 276 (official) horsepower...faster than a vette.... FUCKIN AWESOME!!! (pardon my language, I just couldn't help it)
They only made 500 or so of these, but their owners are very lucky people.
Some other good buicks:
1) 55 century. 0-60 in 9.8 (1.5 secs quicker than the 55 chevy)
2) 70 GS 455 stage I. 0-60 in 5.5, 1/4 in 13.5 at 105.3mph. An awesome sleeper.
Those are just 2.