In a vehicle moving at a "moderate" speed with AC on and windows closed, the cough-jet from an infected person in the back seat can form droplets and a plume of aerosols (avg speed: 10 m/s; ACH < 60 per hr; temp: <25 C; relative humidity < 50%). The plume of aerosols first spread towards the front and turned backwards as it got carried away by the AC streamline. This increases the risk of infecting everyone in the car.