which is the inside lane on a road
Overtaking Overtaking on the inside or undertaking[2][3][4] refers to the practice of overtaking a slower vehicle on a road using the lane that is kerb side of the vehicle being passed; that is to say, a lane to the left of the vehicle in countries where driving is on the left, or a lane to the right of the vehicle in countries where driving is on the right. The practice of passing on the inside, therefore, usually only occurs on a motorway or other road where there is more than one lane in the same direction or when the width of the roads makes this possible (although there may be exceptions in the cases of contraflow bus lanes).
Wing mirror In the 1940s many roads were unpaved and had two lanes, one in each direction. Drivers had to be aware only of traffic on their side and directly behind them (rear view). Due to this, most passenger vehicles with an internal rear-view mirror until the late 1960s had the passenger-side mirror only as an optional addition, as it was considered a luxury.