Keep an eye on the side of the road for bright yellow stars as they indicate a place where a car awaits you. Once you reach it and 'set it free', the vehicle will follow the snowplough staying on the path you clear out. Stars are basically the currency of the game and the more cars you free the more stars you will have in your bankroll. The amount of stars you have at your disposal is displayed in the upper right corner of the screen. Stars can then be used at the lobby screen to unlock more powerful snow ploughs from the garage.