Automotive historians, mechanics, and consumer advocacy reviews frequently cite several notorious transmissions that suffered from chronic engineering flaws, catastrophic component failures, and remarkably short lifespans. Units such as early continuously variable transmissions found in certain economy cars, early dual-clutch gearboxes prone to severe shuddering and overheating, and poorly integrated automatic units from various manufacturers that suffered from premature planetary gear destruction or electronic module failure are universally regarded by the automotive community as some of the worst designs ever mass-produced for the consumer market.