ujm,
“If driving customs are based on local minhagim, how is anyone not from the area to know what the local driving customs are”
There’s no way to know, and it’s almost impossible for a driver in an unfamiliar area to completely “go with the flow” and not cause any annoyance. But there are some broad generalizations that can be made:
1. Nowhere else in the US is driving quite like it is in the NYC metro. So NYers should in general when outside of the NYC metro should give extra space between their vehicle than others (perceived as aggressive), try to avoid changing lanes into tight spaces (perceived as cutting off), avoid quick maneuvers like fast and sudden U-turns (perceived as scary), and accept the fact that OOTers have a slightly slower reaction speed to light changes (they’re not intentionally trying to harm you).
2. Driving is a bit more NY-like inside big Northern cities and parts of South FL (DC, Baltimore, Philly, Boston, Chicago, Miami), but less so in bigger Southern cities (Orlando, Atlanta, St. Louis).
3. For OOT drivers going into NYC, stay alert and even-keeled, and say some tehillim. Short honks are more like communication than rudeness (hey I’m here, ooh guess what the light’s green!). And pedestrians in NYC can chew off metal bumpers.