The Spitfire had the same engine as the Merlin powered
P-51 Mustang. The Mustang had twice the fuel capacity and twice the range of a Spitfire though. Due to its lake of range, the Spitfire was useless as a bomber escort.
For bomber escort and fighter superiority missions, the
P-51 Mustang was the best fighter of WWII. The P-47 was the best fighter-bomber due to its air-cooled radial engine, 8 50-caliber machine guns, and bomb load capacity. Fighters with a liquid-cooled engine like the P-51 and Spitfire were much more vulnerable in ground attack missions.
Well sure, once they added external tanks. :)