Designed by Dante Giacosa, the Fiat 100 engine first appeared in a 633 cc (38.6 cu in) form in the all-new Fiat 600 in 1955. The in-line four-cylinder engine comprised an iron block and an aluminium cylinder head with pushrod actuated valves. The engine was produced at Fiat's Mirafiori (Turin) plant, and then at Bielsko-Biała, and remained in production until 2000, used in Fiat Panda and Fiat Seicento in its last 899 cc (54.9 cu in) capacity version fitted with SPI single-point injection and hydraulic tappets, although slowly being phased out starting from 1985 in favour of the new Fiat FIRE engine.It was also produced until 2008 in the Zastava plants in Kragujevac.