The Mercedes-Benz 300SE Heckflosse were sedan cars that were produced during the years 1959-1968. 

'Heckflosse' in German means 'tailfin' which was a type of tail style that were used in 60's by several brands including Chrysler, Chevrolet and Cadillac. While the purpose of these tail shaped fins in America was to improve the wind resistance at the tail side, Mercedes-Benz's idea to introduce them were to improve the sight line or 'peilstege' (a hypothetical line from someone's eye to what is visualised). 

Mercedes-Benz also introduced the safety steering wheel with the W111 and W112 models. Automatic gearbox, power steering and air-suspension were standard features. 

Mercedes used the tailfin design extensively for their W110, W111 (this was the 220 model that came with a 2.2 litre, 6 cylinder engine) and W112 (this was the 300 SE that came with a powerful 3 litre, 6-cylinder engine) models.