Automotive uses round steel for crankshafts (4140 heat-treated), axles (1045), bolts (8.8-grade alloy steel), and suspension components (Q345). High-strength low-alloy (HSLA) rounds (350-500 MPa yield) reduce weight in chassis parts, improving fuel efficiency. Stainless steel rounds (304, 316) are used for exhaust systems (corrosion resistance) and fuel lines. Cold-drawn rounds with tight tolerances are preferred for precision parts like bearings, ensuring smooth operation and durability under high loads.