The lack of specific details about the people in the true - story of 'Fast Car' leaves a lot to speculation. It could have been someone who was on the fringes of society, trying to make a better life for themselves. It might be a young person who had big dreams but was held back by circumstances. Or it could be an older person who looked back on their youth and a fast - car experience that was a turning point in their life. The songwriter may have chosen not to name the actual people to keep the story more universal and relatable.
There's no clear information on who exactly were the people involved in the true story of 'Fast Car'. It could be the songwriter's own experience, so it might be about the songwriter and their friends or family members.
Since there's not much publicly disclosed about the specific people in the true story behind 'Fast Car', it's possible that it was based on a composite of different people the songwriter had encountered. Maybe it was inspired by a stranger the songwriter met during a journey, or it could be about people in the songwriter's community who had a story related to a fast car, like a local mechanic who always dreamed of a fast car ride to a different place.