Sitting Commuter Pec Stretch
People usually aren't happy while sitting in traffic on their way home from work but you will be if you stretch those pecs while you are waiting for traffic to clear. This is a great stretch to open up your chest and get you more relaxed overall.
You might need to open up your window for this one and you probably only want to do it while the car is stopped at a light. Bring your arms out to the side and bring your chest up and out in front of you. This will open up your chest and the further you move your arms back the more you will feel the stretch in the front of your chest.