Hugo est le plus rapide/vite

Question

Vite is marked wrong. Pourquoi?

Accepted Answer

Bonjour Chris,
'Vite' is an adverb and refers to a verb, not a noun like 'rapide' as it is an adjective.
Hugo court vite = Hugo runs fast
You may hear sports commentators using 'vite' instead of 'rapide' - but 'rapide' should really be used. 
I hope this is helpful.
Bonne journée !

Answer

Chris - you may be interested to read some of the references below on this:

Académie-française categorises “Vite” as both an adverb and an adjective, and used to describe some quick-moving animals, such as “un cheval vite” - suggesting adjectival restriction almost completely to this use.

“Qui se meut avec célérité, avec promptitude ; il ne se dit que des Animaux et de certaines choses dont le mouvement est rapide. Cheval vite, fort vite, vite comme le vent. Il a le pouls fort vite.”

Robert en ligne uses the example of “Le coureur le plus vite” under modern/sports use, and Larousse notes “journalistic” use as an adjective.