The first
Audi raced a DCT in Group B rally in the 1980s. The first production DCT in the US was the 2003 Volkswagen Golf R32 with the DSG — a 6-speed wet-clutch unit.
Going mainstream
The 2008 Mitsubishi Evolution X MR brought DCT (TC-SST) to a sub-$40k Japanese performance car. The 2010 Ford Fiesta brought it (PowerShift dry-clutch) to a sub-$20k subcompact — disastrously, as the dry clutches couldn't handle the heat and the resulting class-action lawsuit cost Ford hundreds of millions.
The performance car
By 2015, every supercar that wasn't a manual had a DCT — Ferrari, McLaren, Porsche PDK, the Corvette C8. The C8's 8-speed Tremec DCT is the first American mass-market sports car DCT.
The point
DCTs shift faster than humans (sub-100ms) and smoother than torque-converter automatics. They also kill the clutch pedal — which is why purists hate them. The 911 GT3 still offers a manual; the C8 doesn't. Take your side.