I haven’t found any evidence that Delaunay painted a car like this 1920 Unic Tourer, but she did work her magic on a 1924 Bugatti T35, a 1925 Citroen B12 (with matching dress) and a 1968 Matra 530.
Ukrainian-born Sonia, married to fellow artist Robert Delaunay, was a key figure in the Parisian Avant-garde. She collaborated with Diaghilev on stage sets and costumes, illustrated covers for Vogue (including one featuring an art car) and had her work exhibited in the Louvre. She owned her own global textiles label Tissus Delaunay and fashion boutique Casa Sonia.
You can read more about her on andalusia.com