To add to your observations regarding the P-51, it should be noted that its primary adversary were later model Messerschmitt 109s, the superior Focke Wulf 190 never reaching the numbers of production the 109 attained. Hitler had banked all on the 109, expecting a short war decided by quantity more than quality. As a result, the 109's ageing airframe was fitted with ever larger and ever thirstier engines. By late in the war, the 109s which scrambled to meet incoming waves of Allied bombers, escorted by p-51s, had the performance to give the Mustangs a run for their money, but quickly had to go back for more fuel. When the 109 climbed back up to the fray, those same p-51s it had engaged could still be waiting.