This is basically the same car as the Buick Regal GS (1997-2004), both of which underpinned the 2003-2005 Impala and Monte Carlo SS. GM had an odd way of classifying both performance and size classes in its days. The Grand Prix was "midsize," and marketed to Accord/Camry/Maxima/Altima buyers, when it was actually sized like the Avalon and Taurus and Intrepid
The Bonneville wasn't much bigger than the Grand Prix, but it was far too upscale even for likes of the Intrepid and Crown Vic. That particular car's SSEi version was packed with the same exact powertrain as the Grand Prix GTP as shown here, but because it was heavier and trained with a longer wheelbase, it got ditched and replaced by a Northstar V8 (GXP) version.
Bonneville got discontinued and replaced by Australian-built G8. Grand Prix sorta continued on. The GTP continued halfway through the Grand Prix's last generation, and got replaced by the LS2-based, yet shorter-displaced "LS4" V8...a true sleeper. (Sadly it wasn't much faster, probably not at all, compared to the N/A V6-powered G6 GXP.)
Most of the "Super Sports" weren't that special, unlike the ones from the 1960s. I could go on and on :)