Research shows that wearing your mask, and opening the front passenger window, and the window behind the driver seat helps to reduce the spread of the novel coronavirus in your vehicle. See this NY Times article.
I am a nurse at Veteran's Affairs Hospital in Rancho Cordova. I am commuting from Pollock Pines or Placerville to VA Hospital. I start work at 8am-4:30pm. There is also another nurse that I car pool with. We have commuter pass from VA/ government.