Magnesium stands out on paper as a strong candidate for vehicle construction. It weighs 75 percent less than steel and 33 percent less than aluminum, reduces noise more effectively than either, and ranks among the most common elements worldwide. Still, the typical car today uses less than 1 percent magnesium by weight. Cost, corrosion issues, and heat management explain why the material falls short of its potential in automotive applications.

Magnesium has a longer automotive past than many realize. Ferdinand Porsche's early Volkswagen concept from the 1930s called for a rear engine light enough to preserve front-end traction. Magnesium fit the weight needs for both the engine block and transmission. VW later established a magnesium foundry in Kassel, Germany, and sourced 60 percent of Norsk Hydro's output from 1951 to 1981, incorporating roughly 20 kilograms per vehicle.

BMW later explored magnesium components in the N52 inline-6 engine. This unit marked the first water-cooled design to feature a magnesium block. Aluminum cylinder liners managed mechanical stresses and bore corrosion, while coolant flowed solely through aluminum sections. The approach succeeded but highlighted the extra measures needed to adapt magnesium for water-cooled use.

Corrosion poses ongoing difficulties for magnesium in engine settings. Exposure to moisture or salt combined with contact to other metals causes it to oxidize and degrade first, as electrons migrate to the more stable metal. This behavior complicates standard multi-material engine builds, demanding extra coatings or isolation strategies to prevent damage.

Magnesium presents fire and budget concerns

Magnesium carries a flammability risk that is sometimes exaggerated. It can ignite and produce intense fires that resist easy extinguishing. For components away from direct combustion zones, everyday operating risks stay low. Certain performance models, such as the Mustang GTD with magnesium wheels, demonstrate viable uses outside engines. Yet concerns linger around internal applications, leading to cautious engineering and regulatory approaches that aluminum avoids.

Price fluctuations add further obstacles. Automotive, aerospace, and defense sectors vie for limited magnesium supplies, much of which comes from China, resulting in unstable costs. European prices rose nearly 100 percent in 2021 due to supply interruptions. Engineers often target magnesium parts for replacement with lower-cost alternatives in later production runs, reversing earlier weight-saving goals.

Magnesium finds success in areas where weight savings matter most and corrosion can be controlled. Examples include steering brackets, dashboard supports, seat frames, and transmission housings. The C6 Chevrolet Corvette ZR1 employs a magnesium engine cradle that cuts weight by 35 percent versus aluminum, and the Porsche 911 GT3 RS uses magnesium wheels for a reported 17.6-pound reduction.

Recycling at end of life creates added issues. Magnesium closely resembles aluminum, leading to frequent contamination in scrap flows and requiring special separation tools.

Magnesium has not proven unsuitable overall. It simply demands more attention, and the industry favors reliable, scalable materials that avoid added complexity. Aluminum continues to address many of magnesium's limitations effectively for now.