There's no single answer to whether a V6 Mustang or Camaro is faster. The speed depends heavily on the *specific year* of each car. Both manufacturers made changes to their V6 engines and transmissions over the years, leading to varying performance figures.
To get a definitive answer, you'd need to specify the exact year and model of both the Mustang and Camaro. Then, you could compare their 0-60 mph times and quarter-mile times from reputable sources like MotorTrend or Car and Driver.