I found my answer:
..."The G8's quickest acceleration runs were actually made with the transmission in Sport mode but left to shift itself. With the blast from zero to 60 mph taking only 5.4 seconds and the quarter-mile flashing by in just 13.7 seconds at 104 mph, this is a stupendously quick car."
The G8 picks up very fast...but loses at the top end. Figures.