The gate is wide enough for that car to get through.
Literal
Gate [topic-は] that car [subj-が] can-pass [extent-ほど] wide.
~ほど ('to the extent of, enough to') is a very useful grammar point — it expresses degree via a clause comparison. Here the clause その車が通れる ('that car can pass') + ほど + 広い = 'wide enough for that car to pass.'