The SD-455 has been accurately described as Pontiac's last stand and the last real muscle car. The SD-455 was a thinly disguised race engine: four-bolt mains, reinforced block, forged pistons, forged connecting rods, nitrided crankshaft, even a provision in the block for a dry sump oiling system. The SD-455's cylinder heads were a free-breathing design patterned after the howling Ram Air IV heads, and the cam was similar to the grind used in the Ram Air IV. In 1973, the SD 455 ran the quarter mile in 13.751 seconds and at a terminal speed of 103.56 mph.