G'day Capt Fathom,
C210 glide ratio of about 12.5 : 1, if I remember correctly.
Beaten by the Mooney at about 14 : 1, I am told.
Not many others come close...
The good ole' C210 has got me back to 'terra firma' in 'silent running' OK - and for that I am grateful to its designers.
C-210's - LUV 'EM!