Passenger Side (2009) on Netflix

Thirty-seven year old Michael, a writer, agrees to drive his thirty-five year old brother Tobey, a recovered junkie, on a series of errands through the Los Angeles area for the day as Tobey's car is out of commission. Beyond a job interview, Michael expects the errands are mundane everyday tasks like going to the post office. After the first few stops, at which Michael is to sit in the car while Tobey does his business, Michael comes to the quick realization that these errands are not mundane in nature, and believes Tobey may be trying to score some drugs. Tobey eventually divulges the nature of his singular mission for the day. Although Michael doesn't fully support Tobey's mission, he agrees to continue chauffeuring Tobey to the end. This singular task is not as easy to accomplish as it appears on the surface as Michael and Tobey get into one misadventure after another. But during their day together, the brothers are able to talk about the current state of their individual lives, Michael's which takes on special meaning in light of Tobey's mission.