In "Batman Begins" by Christopher Nolan there is a chase scene in which police are chasing the batmobile. One of the Police officers is talking on the radio to the dispatch, while he is catching up to Batman's batmobile from the back. He says "I'm coming right up on his butt". From the context, I understand that it simply means, that he is "getting closer to the rear end of his batmobile" But I can't find any definition in a dictionary for a phrasal verb like this. The only definition I found, which is similar is:
Come right up: —used by someone (such as a waiter) to say that something will be served or delivered very quickly "I'd like a turkey sandwich and a glass of lemonade, please." "Coming right up!" (source: Merriam Webster)
I even thought these are two phrasal verbs combined together, consisting of "come on" & "right up". Can someone provide a definition for this phrase?