If your vehicle is showing hot, burning metal or burning rubber smell after driving, here are the most likely causes and the parts you'll need to fix each one.
A seized brake caliper, stuck slide pins, or an engaged parking brake causes the brake pads to constantly rub against the rotor. This generates immense heat, resulting in a sharp, acrid burning metal or friction material smell near the wheels.
Engine oil leaking from a failing gasket (commonly the valve cover) drips directly onto the extremely hot exhaust manifold or pipes. This instantly vaporizes the oil, creating a pungent burning smell that enters the cabin through the vents.
A worn drive belt, weak tensioner, or a seized accessory pulley (like an A/C compressor or alternator) causes the belt to slip over the pulleys. The resulting friction melts the belt, producing a strong burning rubber smell from under the hood.
In manual vehicles, a worn clutch disc or improper driving technique causes the clutch to slip against the flywheel under load. This generates extreme heat and a distinct burning friction material smell, especially when accelerating or driving uphill.
A plastic bag or road debris caught under the car on the exhaust pipe, or a misrouted rubber hose/wire loom resting against the exhaust manifold after recent engine work, will melt and cause a terrible burning rubber or plastic smell.