While the ZL1 was given drag race considerations, the Z/28 was molded as a pure track car. One nod to this single-mindedness is the Torsen helical limited-slip differential. This little piece of engineering cut 0.7 seconds per lap off the Milford road course times. It offers improved ABS functions during cornering and more traction on corner exit. The downside is that it's not as robust for drag racing, but then again, that's why they sell the COPO.