Final answer:
To avoid a car ahead with a car beside you in the left lane, decelerate and increase following distance, change lanes to the right when clear, or use hazard lights while staying in your lane, all while maintaining situational awareness and following rules of defensive driving.
Step-by-step explanation:
If there is a car beside you in the left lane and you need to avoid a car ahead, the most immediate course of action would be to decelerate and increase the distance between you and the obstacle ahead, if braking is safe to do considering the distance of the car behind you. If possible, smoothly change lanes to the right when it is safe without impeding other traffic, provided there is space to do so. If there's no time to change lanes or if other lanes are not clear, then reducing your speed while staying in your current lane and signaling your distress (e.g., using hazard lights) could also alert the drivers around you to your situation.
It is important to maintain situational awareness in such circumstances, continuously checking your mirrors and blind spots before making any maneuvers to ensure that you don't endanger yourself or other road users. Always follow the rules of the road and the principles of defensive driving.