Chinese in Avatar

Legend of Korra, “When Extremes Meet”

The characters above the hood of the police car read rather unsurprisingly as follows:

共和城 gònghéchéng as I’ve discussed before simply reads “Republic City.”
警隊 jǐngduì differs from the usual police jargon we see in the shows. 警 jǐng is an abbreviation for “police” (警察 jǐngchá) and 隊 duì (trad.; simp. 队) means “squadron,” “team,” or “group.”

So共和城警隊 gònghéchéngjǐngduì = “Republic City Police Squadron”