Not as fast as a Mustang, - well, overlapping.
And nowhere near a Spitfire from the same era in ROC. Except very high up?
I have one good document of a 109G. tested in 1944 (ahh, Gripen), and it's rather in the same ballpark, some 6 mins+ to 20K.
Now there is one thing about the DB that I wanted to mention. Due to material problems etc.(war situation) the legend goes that they were not up to what the design was about. So would that apply to top-notch measurements, or just the lifetime?
There are some documents about this I belive, but I got on the lead from Rall, who was not at all happy with his DB and his 109 when he had be jocking around with Allisons, Merlins and P&W's, P51, Spitty, P47 and the P38.
Anyway, there are always grayzones.