Not sure how much surface you have to stain....
Red Ochre - 100 grams (about .22 lbs) for $3.95
500 grams (about 1.1 lbs) for $13.65
See technical data (page down) on this site:https://www.earthpigments.com/red-ocher ... gLV6vD_BwE
Practice your strength of solution and application method on some scrap wood, first, before working on your car's wood.