In 1955 FIAT replaced its revolutionary Topolino small saloon, which had been around in one form or another since 1936, introducing the successor '600' model at that year's Geneva Salon.

Historically significant as the first rear-engined FIAT, the 600 was a masterpiece of automotive packaging, cramming accommodation for four into the same 2,000mm wheelbase as the outgoing two-seater Topolino, which it undercut on price.

The integral chassis/body featured independent suspension all round, while the 633cc water-cooled four-cylinder overhead-valve engine produced 22bhp, which was good enough for a top speed of 62mph.

The most significant upgrade to this outstandingly successful design occurred in 1960 with the introduction of the 600D, which featured a 767cc engine, altered gearing and greatly improved performance.

Although conceived as basic transport for the masses, the 600 would prove to be an extremely capable competition car; examples modified by Carlo Abarth turning in giant-kil...