I wouldn't put much faith into those turn diagrams. They're estimates, and they can't even get the basic data such as power outputs. The Clmax are assumed, which makes the dataset as good as any guess...
The best you can do is to dig up some British source for the Spitfire, and some German sources for the 109, preferably in comparable conditions, and then see what gives.
For the 109, there are plentyful of German sources for turn.
The British estimate gives it 206 meters for the Spitfire, and 260 meters for the 109E, at 12 000 feet or 3657 meter altitude.
A Messerschmitt company document from August 1940 gives the turn time for a 360 degree sustained turn with 5-min power as 18.92 seconds, and the turn radius as 203 meters.
The Bf 109E manual gives the smallest turn radiuses as the follows :
W/o flaps, 0 meter altitude : 170 m
W. flaps, 0 meter altitude : 125 m
W/o flaps, 6000 meter altitude : 320 m
W. flaps, 6000 meter altitude : 230 m
A particularly interesting thing is the use of combat flaps. The 109E had combat flaps, and it could use them up to fairly high airspeeds. The Spitfire flaps could be only used for landing (having only 2 positions, up and down). As seen, flaps have a very marked effect on turn radius, and it could be entirely possible that the Emil can get minimally smaller turning radiuses by using them (ie. using flaps 109E: 230m/6000m vs. Spit : 206m/3600m, and altitude has marked negative effect on turn radius)
The British give something like 24-25 seconds for the 109E, so I presume they grossly overstated turn times for the aircraft, given the German figures. I presume that is because the only Bf 109E available for evalutation for the Brits was one that was originally crashlanded and captured by the French back in 1939, who later handed over the Brits, but the aircraft was in fairly rough shape even back in the French evaluations reports which mention it's poor powerplant condition.
The British estimate give ca 18.5 seconds for the Spit, which is pretty much the same as the Bf 109E turn time. The same can be said about turn radiuses, 20-30 meter differences in turn radius is good for an 'academic' debate, but it practice you can wipe your butt with such 'advantage'.