The terms "turbo" and "turbos" relate primarily to turbochargers in automotive contexts. Here's the breakdown:

1. Turbo (singular):
Refers to a turbocharger, a device that forces extra air into an engine to boost power.
Example: "My car has a turbo for better performance."
2. Turbos (plural):
The informal plural of "turbo," used when referring to multiple turbochargers.
Example: "The engine uses twin turbos for increased efficiency."
In technical writing, "turbochargers" is more formal, but "turbos" is common in casual usage.
3. Other Uses:
Computing: "Turbo" was historically a brand term (e.g., "Turbo button" on PCs), not pluralized.
Proper Nouns: Titles like the movie Turbo remain singular; plural would depend on context (e.g., "three Turbos raced").
Summary: Use "turbo" for one and "turbos" for multiple turbochargers. The distinction is casual vs. technical, with "turbos" widely accepted in everyday language.