In the automotive industry, high-strength steel is used extensively to improve the strength and safety of vehicles while reducing weight. 

The different color grades of high-strength steel used in cars generally refer to their strength level, as follows:

This color code is typically used to indicate mild steel, which has a relatively low tensile strength and is used for non-critical parts such as brackets and supports.

This color code typically indicates high-strength low-alloy (HSLA) steel, which has a higher tensile strength than mild steel but is still relatively easy to form and weld. HSLA steel is commonly used for body panels and structural components.

This color code typically indicates advanced high-strength steel (AHSS), which has a very high tensile strength and is used for critical structural components such as roof pillars and door beams. AHSS includes various types of steel, such as dual-phase steel, transformation-induced plasticity (TRIP) steel, and martensitic steel.

This color code typically indicates ultra-high-strength steel (UHSS), which has extremely high tensile strength and is used for parts that require the highest level of strength and durability, such as suspension components and seat frames. UHSS includes materials such as boron steel and press-hardened steel.

It's worth noting that the color codes used for steel grades may vary depending on the manufacturer and region, so it's important to consult the relevant specifications for a specific application.

For detailed information, please watch the full video.