Translation:The youngest man is also the fastest.
I read your comment, and it's a fair & reasonable presumption. But I wasn't sure if what you said was what they had in mind (accidentally didn't consider groups larger than 2) , or if νεοτερος was in fact intended to mean "fastest" by some stretch of the imagination (i.e. if somehow it works in Greek. Ya never know!).
We are aware and will add the sentence with "too" but do not prefer it since it diverges unnecessarily from the Greek word order.
The youngest/younger man is the fastest/faster one too. or The youngest/younger man is the fastest/faster too. and The youngest/younger man is the fastest/faster man too.
There are 2x2 = 4 translations: The younger man is the faster. The younger man is the fastest. The youngest man is the faster. The youngest man is the fastest.
«Modern Greek does not distinguish between the largest house and the larger house, both are το μεγαλύτερο σπίτι.» https://en.m.wikipedia.org/wiki/Modern_Greek_grammar
Well! My Greek intuition says that in this phrase both are in superlative. The word νεότατος is not used with an article anymore,it is not but an old fashioned word and I incline not to use it anymore, unless I want to be veeery formal! I guess it happens to many Greek speakers. More usual, but not wrong is the word γρηγορότερος, the periphrastic form is ο πιο γρήγορος. Since there's no other younger or faster to compare with this, it is the most likely answer to this phrase.
It is a bit confusing, but the form in -οτατος, -ώτατος is a bit under extinction, slowly, but steadily! ;)
Example: ο καλός, ο καλύτερος, ο πιο καλός but not o κάλλιστος
Ο νέος ο νεοτερος (ο νεότατος) ο νεώτερος, or, ο πιο νέος
Ο γρήγορος, ο γρηγορότερος, ο πιο γρήγορος
Ο μεγάλος ο μεγαλύτερος, (ο μέγιστος) or ο πιο μεγάλος
Why a comparative can be used as a superlative? It is implied από όλους.