Someone on a Buick forum found these two videos:
A 1973 Buick GS 455.
YouTube - 1973 Buick GS 455 road test
Watch at 2:40 for the slalom test; it does quite well for a big and heavy car. Also note at 4:55... going through a curve at over 75 mph. The 15.3 second 1/4 mile time is also good for a heavy car with a desmogged, low-compression engine and what is probably high gearing.
1972 Buick Riviera GS
YouTube - 1972 Buick Riviera GS road test