When I read your first post, I incorrectly thought you were saying your wife was driving in one car and her friends in another. And you wanted to tell her friends which road to take. Hence my "inappropriate control" statement.

I still think you worries are overblown.

But if your wife was accepting a ride from others I would consider it perfectly acceptable for her to say she is not comfortable on two lane roads and would prefer a different route. Equally appropriate would have been for the car's driver to say "no" (this would be maybe a bit rude or insensitive, but still within their perogative). Equally appropriate after that refusal would have been for your wife to decline their offer for a ride and drive her own car.

Around here, a four lane road clogged with cars and constuction would be much MORE dangerous than a less traveled two laner, but of course your neck of the woods might be different.