The Fiat 520 is a name of two different Fiat produced car in 1920s.

520 "Superfiat" (1921–1922)

Fiat's entry in the luxury car market, the 520 "Superfiat" was equipped with a V12 engine

V12 engine

A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft....

 of 6,805 cc producing a claimed 90 bhp. For several years in the early 1920s it was the only car in the world offered with a V12 engine.

520 (1927–1930)

Fiat's upper middle class car in the later 1920s was also designated as the Fiat 520, but was smaller and more modestly powered than its earlier namesake.

During the early decades of the 20th century European automakers, once steering wheel

Steering wheel

A steering wheel is a type of steering control in vehicles and vessels ....

s had replaced centrally positioned steering tiller

Tiller

A tiller or till is a lever attached to a rudder post or rudder stock of a boat that provides leverage for the helmsman to turn the rudder...

s, tended to place the driver and his steering wheel on the right side of the car regardless of any local regulations or conventions concerning which side of the road cars should be driven. By the 1920s, as the number of wheeled vehicles on the roads increased, clearer consensus had become necessary in the more populous parts of Italy about the need for everyone to drive along the right side of the road. The 1927 Fiat 520 was one of the first cars, presumably in recognition of this trend, to place the steering wheel on the left side of the car.

The 520 was replaced by the Fiat 521

Fiat 521

The Fiat 521 is a passenger car produced by Fiat between 1928 and 1931. The 521 was derived from predecessor model , it had a bigger engine and chassis. The 521 C was shorter variant of this car. This car was produced outside Italy, most notably at the Fiat-NSU plant in Heilbronn, starting in 1930...

 in 1928, although the 520 appears to have continued in production until 1929, by when more than 20,000 six-cylinder Fiat 520s had been produced.

Engines

Model	Years	Engine	Displacement	Power	Fuel system
520	1927–29	straight-6 Straight-6 The straight-six engine or inline-six engine is a six-cylinder internal combustion engine with all six cylinders mounted in a straight line along the crankcase...  sidevalve	2244 cc	46 hp	single carburetor Carburetor A carburetor , carburettor, or carburetter is a device that blends air and fuel for an internal combustion engine. It is sometimes shortened to carb in North America and the United Kingdom....
520 T	1928–30	straight-6 Straight-6 The straight-six engine or inline-six engine is a six-cylinder internal combustion engine with all six cylinders mounted in a straight line along the crankcase...  sidevalve	1866 cc	35 hp	single carburetor Carburetor A carburetor , carburettor, or carburetter is a device that blends air and fuel for an internal combustion engine. It is sometimes shortened to carb in North America and the United Kingdom....