Generally, a
Chevy Corvette is faster than a Ford Mustang. However, this isn't a simple yes/no answer. The speed difference depends heavily on the specific model year and trim level of each car. There are high-performance Mustangs (like the Shelby GT500) that can rival or even exceed the speed of some Corvette models, and conversely, there are entry-level Corvettes that might be slower than higher-end Mustangs.
To make a proper comparison, you'd need to specify the exact make, model, and year of both the Mustang and Corvette in question.
