From Wikipedia:

In late 1944, Kurt Tank reported that while flying an unarmed Ta 152H to a meeting at the Focke-Wulf plant in Cottbus, he saw two P-51 Mustangs. He made his escape by engaging the MW 50 boost, opening the throttle wide to gain maximum speed to escape the enemy fighters, and left the two Mustangs behind him.

Though far more likely explanation is they simply never saw him as no contact or chase was ever mentioned in reports and he drastically inflated the tail... rather likely given that at low level the P-51D was actually faster then the very heavy and very draggy (due to the huge wings) 152H was.