Answer:
I'm not sure which online dictionary it is, but I'm using dictionary.com here.
The definition there is "no longer in general use; fallen into disuse/of a discarded or outmoded type; out of date/ no longer in use/ (of a linguistic form) especially, out of use for at least the past century.
The second definition goes well with the context of a vehicle.
(I don't know what your options are I am simply using an example word, tell me the options if you would like so I can change my answer.)
Based on the definition, the best synonym for obselete would be outdated.
Explanation:
