This car was, at least in a way, a leftover Series 1 Cadillac CTS-V. Both shared the same Vortec 6000 engine block, although the G8 GT's variant was not the Corvette-derived LS2, but rather the truck-oriented L76. With that being said, the "GMC Sierra 1500 sedan with a Pontiac badge" crosses the finish line around the 12.8-mile German north loop circuit 13 seconds earlier than the "Chevy Corvette sedan with a Cadillac badge" does.
2008 Pontiac G8 GT
Claimed Power: 361 hp @ 5300 rpm
Claimed Torque: 385 lb-ft @ 4400 rpm
Bore x Stroke: 101.6 mm x 92 mm
Number of Cylinders: 8
Boost Pressure: naturally aspirated
BMEP d: 10.0 bar
VE un-boost: 100.00%
VE boost: 100.00%
MPS @ Peak Power: 18 m/s
Actual Power: 391 hp @ 5870 rpm
Actual Torque: 385 lb-ft @ 4400 rpm
Drivetrain: RWD; 6AT
Estimated Weight: 3988 lb
0-60 MPH: 5.3 sec
0-100 MPH: 11.4 sec
0-150 MPH: 30.4 sec
1/4-Mile (street): 13.7 sec @ 110 mph
1/4-Mile (drag): 12.8 sec @ 106 mph
Top Speed: 175 mph
Motor Trend Figure-8: 25.3 sec @ 0.80 G
Nürburgring Nordschleife: 8:15
Top Gear Test Track (Power Lap): 1:27
https://docs.google.com/spreadsheets/d/11T6iUr6uQ_TkqqFB1nPvV0malo9X5HgXlK3JZ2du1RA/edit?usp=sharing