I'm going to skip around a little, going from stuff that's obviously simple, to much more complicated dialog. First, the title.
rei = cold
shoku = food
sousakan = investigator
Tori Miki chose to call this series "Frozen Food Agent" in English. The "French Connection" subtitle already in English is in part a reference to the movie of the same name, as well as being a pun on the materials being smuggled.
In the first panel, the cop says -
すまんな けんもん だ
suman-na = A casual version of sumimasen - "sorry", or "excuse me"
kenmon = Inspection
da = A casual version of "desu", meaning "is".
There are any number of ways of translating this. I originally wanted to use, "Excuse me, this is a checkpoint", but it didn't fit in the balloon easily. Then I figured that "Sorry, checkpoint" worked just as well, while also conveying the sense that the cop is being business-like and is not really that sorry.
The driver replies -
えーっ！? ナビ には ぜんぜん でてなかった ざんす よ
Eh = what?
nabi = navigator, the Japanese version of GPS
ni wa = from + topic marker
zenzen = nothing
detenakatta = polite version of "came out"
zansu = see below note.
yo = emphasizing particle.
Eh!? GPS . from . nothing . came out (!)
Literally, "What! Nothing came out from GPS."
I chose to render this as "Ehh? My GPS didn't say anything about a checkpoint!"
Normally, in polite speech the last part would be "detenakatta desu yo". However, Tori Miki decided to give the character an accent to emphasize his being French, changing "desu" to "zan-su", resulting in the character coming across as being really effeminate. I could have treated the character as having a lisp, ("my GPeth didn't thay anything...") but, it wouldn't have been the same thing. Instead, I just left the "su" at the end as-is.
To be continued.