Final answer:
The correct word to complete the sentence is 'down'. It makes the sentence read, 'We will get there faster the highway down via'.
Step-by-step explanation:
The correct word to fill in the blank in the sentence, 'We will get there faster the highway __ via' is 'down'. You would use the word 'down' to indicate direction or path. So the completed sentence would be 'We will get there faster the highway down via'.
Learn more about Prepositions