In an automobile, you can find many different types of steel being used.
The chassis, transmission, axles, saloon area, load body, etc are made out of different composites of steel.

Types of steel used in car manufacturing:

Advanced high-strength steel (AHSS): this type is 10% lighter than mild steel and stronger. It is used all over the car body.

Stainless steel: widely used in automobiles. Especially in Bus bodies and trucks. Usually in exhausts and other parts that are exposed to harsh conditions

High-strength low-alloy (HSLA) steel: usually for frames because it's strong, formable, and cost-efficient.

Ultra-high strength steel (UHSS): rigid and resistant to impact.

Galvanized steel: it is rust-resistant and can make up to 80% of vehicles.

High carbon steel: used for frames, chassis, door panels, and support beams as it is resistant to wear and tear.

Tesla Cybertruck

Advantages of steel in automotive manufacturing

For car bodies, low-carbon steel is typically the most suitable choice. Here's why:

Formability: Low carbon steel (also known as mild steel) has excellent ductility, making it easier to form into complex shapes required for car body panels.

Weldability: It can be easily welded, which is essential for assembling various parts of a car body.

Cost-effectiveness: Low-carbon steel is generally less expensive than high-carbon or stainless steel, making it a more economical choice for mass production.

Weight Considerations: While low-carbon steels are heavier than some alternatives, they provide a good balance between weight and strength for automotive applications.

High carbon steel is typically too brittle for car bodies, as it can crack under impact. Stainless steel offers excellent corrosion resistance but is more expensive and less ductile than low-carbon steel, making it less common for general car body use. However, stainless steel may be used in specific applications, such as exhaust systems or trim components, where corrosion resistance is crucial.

Why is steel better than aluminum for car making:

Carbon fiber part construction and autoclaving are still exceptionally expensive, as all the parts must be cut from cloth and layered in a mold which then must be resin injected and placed under vacuum, including the fully constructed "crash shell/cell" (where the driver and passengers reside) then be heated in a giant oven while still under vacuum. An autoclave large enough to do this task is prohibitively expensive. Also, makers who use many CF parts have several such units.

Carbon fiber can deform, thus absorbing crash energy, often without the part being destroyed.

They will need repainting, but not necessarily replacing.

The weaves in the fiber can also be directionally controlled, so that the designer can very precisely guide the lines of force, where energy will go in a crash.

As aluminum is not a fiber, it cannot be designed to take advantage of this property. Aluminum will always be destroyed. Aluminum is strong and light enough to be used in many areas of the overall design of the vehicle, especially in places where it's just too difficult to make a traditional CF part.

Advances have been made to carbon fiber since the McLaren F1, namely 'Carbotanium'.

As it sounds, this is a weave of carbon fiber where there are titanium strands interwoven.

And it's *10x stronger* than standard carbon fiber.

Many areas of a "typical" (in quotations because there is no typical) car body are formed from a 22 or 24-gauge cold-rolled sheet, often galvanized or with some other corrosion inhibitor added. Some use hot-rolled stuff, some use aluminum of varying alloys, some use hunks of magnesium here and there, and some use stainless steel.

The original VW Beetle was all rounded and stuffed, as a result, the material could be made much thinner than cars with large flat surfaces. This translated into a light, cheap car.

In conclusion, one family of materials is not stronger than the other. The family of stainless steels includes materials that are hard and soft, strong and weak, flexible and rigid, and cost-competitive and outlandishly expensive. So does the family of carbon steels. Instead, you need to select based on the individual design criteria required by each application.