Use ride-sharing once a week.
Considering the fact that using a car costs an average of 50¢/km and this cost seriously grows during times of heavy traffic, it quickly becomes less expensive to adapt the way you travel and use other options than the car from time to time.
Beyond savings, lowering the amount of cars on the routes, especially in busy urban areas (where options are usually numerous) can help dramatically reduce pollution.
Up for a challenge after summer time? One day per week, use any other transportation means, share a ride and a moment with someone.
Keep it up! See you tomorrow for another tip!