Good questions, all. I think there is a boundary somewhere between different minhagim within derech eretz and amhaartzuts. We have gemoras dealing with things like drinking a reviis (not one gulp and not three, Beitza ~ 25), someone should write same for driving. One good place to start is US gov highway survey, do not remember exact name, where they installed cameras in 1000s of cars and then analyzed what was causing accidents. One result: number of sharp stops is a good predictor of accidents.
Maybe, look at accident rates per county v. population density and see where safer drivers live. Obviously, the fact that you live a dangerous place is not an excuse but a reason to be even safer there.