The motor in question is called the GMC Twin Six, and it was GM's last-ever V12 to be produced for road use. It wasn't even used in a passenger car. Instead, the Twin Six pulled its weight under ...

The power output is not what you would typically expect from an 11.5-liter V12, and it is nowhere near as powerful as the most potent engines GMC has built. However, it produces 630 pound-feet of ...