In 1973, Hot Wheels introduced fewer new lines, focusing mainly on continuing and refining existing series. The lines active in 1973 include:

1. Mainline Series: The core lineup of Hot Wheels cars for this year, including a variety of vehicles across different styles.
2. Sizzlers (continuation): The battery-powered cars continued to be part of the lineup in 1973.
3. Rrrumblers (continuation): The motorcycle series also remained in production with new models.

Hot Wheels scaled back production in 1973 due to the oil crisis, leading to a focus on fewer new releases and a shift away from the more complex, larger lines introduced in earlier years.