FWIW, and not having gotten to this exercise yet, I interpret the sentence in the context of driving, with one driver choosing to pass another in a not-so-good place. As to the translation, I would expect to hear "ON a curve" much more often than "IN a curve," at least in the Northeast/Mid-Atlantic regions in the US.

In looks less used, but possible https://books.google.com/ngrams/graph?content=car+in+a+curve%2Ccar+on+a+curve

On a curve is accepted.