[header] How to remove soda stains from a car's interior [title] Dilute the stain with water. [step] If you just spilled soda in your car, act immediately by diluting the stain. Pour cool water over the entire stain, wetting but not drenching the stain. 
Then blot it with a clean cloth. [substeps] Adding water keeps the stain at the surface of the upholstery and prevents it from setting.