Heartaches (1981)
Heartaches is a 1981 comedy motion-picture written by Terence Heffman and directed by Donald Shebib. It stars Margot Kidder, Annie Potts, Winston Rekert and Robert Carradine. The movie is about a young woman, Potts, married to a stock car racer and carrying his friends' child. As she flees that scene, her husband (Carradine) races alongside her bus. On this bus, Potts' character meets the free spirited Kidder and the two women move in together planning to raise the baby. Dealing with romance and poverty, they learn that they have more in common than they thought.
More at Wikipedia.