Part of mpg or mph (3)
I believe the answer is:
per
(Other definitions for per that I've seen before include "Preposition indicating by means of" , "According to" , "Preposition meaning for each" , "For each or every" .)
I believe the answer is:
per
(Other definitions for per that I've seen before include "Preposition indicating by means of" , "According to" , "Preposition meaning for each" , "For each or every" .)