By the early 20th century Syracuse became famous for production of Smith Corona typewriters, Syracuse China, Nettleton shoes, bicycles, wax candles and the Franklin, an ahead-of-its-time automobile with an air-cooled engine.

FORBES: Willis Carrier's Ghost

To meet a target price of 1, 000 marks, approved by the new German chancellor, Adolf Hitler, Porsche devised a rear-mounted, lightweight and air-cooled engine that avoided the need for a heavy radiator.

ECONOMIST: The VW Beetle

One is exhaust gas recirculation, which pumps cooled exhaust back into the engine air intake, lowering the combustion temperature and reducing NOx formation.

FORBES: Clearing the Air