* Condition of the cars: A meticulously restored and maintained 1969 Charger RT in perfect condition will perform better than a neglected, poorly maintained one. The same applies to the Mustang GT.
* Modifications: Any aftermarket modifications to either car drastically alter the outcome. A heavily modified Mustang GT could easily beat a stock Charger RT. Conversely, a mildly modified Charger could potentially outperform a stock Mustang.
* Drivers: Skill significantly impacts the result. A skilled driver can extract more performance from either car.
* Track conditions: The type of track (drag strip, road course) and weather conditions will influence performance. A drag strip favors the car with better initial acceleration, while a road course rewards handling and braking.
Generally speaking:
* Drag Race (1/4 mile): The 1969 Charger RT, with its massive big-block V8, likely had a significant advantage in raw horsepower and torque *if both cars are stock*. However, modern traction control and superior aerodynamics could give the Mustang GT an edge. It would be a close race.
* Road Course: The 2008 Mustang GT would almost certainly win. Its independent rear suspension, superior brakes, modern tires, and refined handling would give it a considerable advantage over the Charger's live rear axle and less advanced technology.
In short: There's no definitive answer without specifying the condition, modifications, drivers, and racing environment. But, assuming both cars are stock and racing on a drag strip, the Charger might edge out a win. On a road course, the Mustang would likely be the victor.