* P-51A/B/C: These early models, with the Merlin 60 series engine, had a top speed of around 425 mph (684 km/h).
* P-51D/K: These later models, featuring the powerful Merlin 66 series engine, could reach a top speed of 440 mph (708 km/h).
It's important to note that these speeds were achieved at high altitude and with a clean configuration (no external stores or armament). In real-world operational conditions, the top speed would be lower.