Enter the limited-slip differential, like the Torsen-branded unit used in the 2013 Scion FR-S (and its cross-brand sibling, the Subaru BRZ). The job of a limited-slip differential is to transfer torque from a wheel that’s lost traction to a wheel that still has traction.
Without getting into too much driving physics, think about what happens as you head into a right hand corner. At turn-in, you transfer weight to the outside (left side) wheel of the car, as you lighten the inside wheel.
Get on the power at the apex of the corner without a limited slip differential, and you’ll likely spin the inside wheel, since it now has less traction than the outside wheel. With a limited slip differential, torque would be distributed from the wheel that’s lost traction to the wheel that still has it.
The benefits of a limited slip differential carry over to street driving as well, since cornering on wet or icy roads can also create a loss of traction. It’s important to note that even the best differential can’t create grip, but it can optimize the traction that’s available to the tires at a given moment.
There’s a bit more to the puzzle than we’ve outlined here, since factors like tire compound and the car’s electronic stability control also come into play, but the net result is this: a limited slip differential will make you faster around a track and safer on the street.