At the 1948 Mechanical Enginerring Exhibition in Turin, a new series of tractors had been shown to the puplic for the first time. March the following year, at the Agriculture and Horse Fair at Verona in 1949, Fiat started taking orders for their new 600 series tractors.
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This new medium size series consisted of three variants. The 600 four wheeled tractor. The 601 crawler tractor. And the rarer 602 "tricycle" tractor.
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Like the 700 series, Fiat made sure the tractors were priced competitively. The Fiat 600 series were the cheapest tractors in their segment. 
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The new engine was designed to run on petrol or diesel, and delivered 18 hp on petrol and 22 hp on diesel at 1.400 rpm with a displacement of 2,270cc.
 
This new engine did however raise some questions from costumers.
First, - it didn't come with an electric starter as standard nor an option, at a time when direct competitors such as Ford and Ferguson were offering this as an option to their costumers. 
But since the Fiat was cheaper than its competitors, and many Italian farmers had no mains electricity to help maintain the battery, this wasn't a deal breaker. 
Second, - the 600 series engines reverted to side-valves, rather than the 700 series overhead valves.
Fiat claimed, and rightfully so at the time, that the side-valve design provided a more efficient combustion of petrol, as the piston at top dead center came close to the cylinder head, providing a great amount of squish-turbulence for mixing the air-fuel mixture. This however, didn't apply when running on diesel.
Probably, the main reason for Fiat to revert to side valves was the simplicity, reliability, low part count, low cost, low weight, compactness and insensitivity to low-octane fuel, that this design provided.
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Another new but unique feature of the 600 series was the chassis. Composed of a cast monoblock, acting as the engine crankcase, gearbox and differential casing all in one. This innovative "tub" design added higher rigidity, but was more expensive to manufacture. This was in part cushioned by the savings made on the development of the 601 crawler version, as the chassis could be used as base for all configurations.
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The new gearbox was a simpler 4 speed gearbox, compared to the 700 series 3 speed with reduction gear. But the extra gear addressed the speed issue that contractors had with the 700 series.
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As an option, the Fiat 600 series were available with a simple mechanical three-point hitch system, to which Fiat started offering a series of dedicated implements, such as one and two furrow ploughs, ridging ploughs, sprayers, lateral and rear mower bars, and more.
 
The Fiat 600 series were an instant success, with the 600 and 601 being the best selling tractors on the Italian market in 1949 and 1950.
But production only lasted three years, as Fiat quickly found ways to improve on the 600 series design, which would turn into the famous 25 series.
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