The term "soups up" typically refers to improving or enhancing something. In the context of an automobile, it could mean modifying the car to make it faster or more powerful. However, antonyms for "soups up" could include terms such as "downgrades," "dumbs down," or "deliberately makes worse." These words suggest a deliberate effort to reduce the quality or performance of something, rather than improving it. In the context of a vehicle, this might involve removing features or components that improve performance, or intentionally using lower-quality materials. Overall, antonyms for "soups up" imply a negative or detrimental effect, rather than a positive one.