Questions & Answers about Мы ехали по горной дороге и молчали.
Ехали (imperfective) focuses on the process: you were in motion at that time.
Поехали (perfective, with по-) usually signals the start of movement or a completed departure (often like we set off / we started to go). In this sentence, the idea is “during the journey,” so ехали fits.
Ехать means to go/travel by vehicle in general. It doesn’t specify whether you’re driving or just a passenger. Context can imply:
- We were driving (if you know they were in a car and one of them drove)
- We were riding (bus/train, as passengers)
- We were traveling (neutral)