Chevrolet 2000 Lumina Owner's Manual page 226

The tethered cap is behind a hinged door on the driver's
side of your vehicle.
6-6
While refueling, let the cap hang by the tether below the
fuel fill opening.
To remove the cap, turn it slowly to the left
(counterclockwise). The cap has a spring in it; if you let
go of the cap too soon, it will spring back to the right.