by J Kraus
The Fiat 600, today mostly overshadowed by its smaller brother the 500, was the car that put post-war Italy on the road. Introduced in 1955, the 600 was one of the many miniscule masterpieces that emerged from the brilliant mind of Dante Giacosa.
Signore Giacosa, like many early automotive pioneers, was a true designer who not only oversaw engineering of the chassis and drive train, but also supervised body and interior design. This resulted in a unity of style, function and clarity of purpose that is all but impossible to find today, when car designs are the product of too many chefs.
The 600 was conceived as the post-war replacement for the Giacosa-designed 500 Topolino. Due to the increasing popularity of the larger four-place Topolino Belvedere, it was decided to build the new 600 as a four-seater only, with no two-place version. Due to the high price of fuel in post-war Italy, the new car was to be designed as small, light, inexpensive and economical to operate as possible.
To achieve this goal, Dante’s team first set about building a seating buck to just barely accommodate four passengers. Various configurations of mechanical components were then arranged around it as closely and efficiently as possible in order to keep overall dimensions and weight to an absolute minimum. Front wheel drive was considered, but rejected early on for cost reasons. That left a rear engine-rear drive layout as the only viable space-efficient option. After brief experimentation with an intriguing 150 degree V-twin air-cooled flathead with valves set at a 45 degree-angle to the cylinder bores, a more conventional water-cooled in-line four-cylinder OHV engine layout was selected.
Novel design solutions were integrated throughout the car to enhance simplicity and reduce weight, size and cost. The engine was a prime example. The aluminium cylinder head incorporated a cast-in intake manifold. The head itself was a crossflow design, a comparative rarity at the time for mass-produced inline engines. The free breathing potential of the crossflow head facilitated sizable power increases by tuning firms, epitomized by the renowned Abarth & Cie.
The water pump, cooling fan and radiator were all placed alongside the engine to reduce the required length of the engine compartment. Instead of a dedicated heater core, a portion of the air blown through the radiator was ducted forward through the centre tunnel to heat the cabin and defrost the windscreen.
The new powerplant, developed by Giacosa and Saroglia, remained in production through 1986, over the decades powering some of Italy’s most beloved automobiles; the 600 and its derivatives as well as the 850, 127 and Autobianchi A112. The engine was coupled to a four-speed transaxle, with synchromesh on second through fourth gears.
Rear suspension was a unique ‘semi-semi’ trailing arm setup. Rather than the normal 15-20 degree (from lateral) swing axis of conventional semi-trailing arm suspensions (as later popularized by BMW, Porsche, Mercedes-Benz and others), the 600’s arms were set at around 50 degrees. This produced much more camber change with vertical wheel movement than these later systems, but the correspondingly reduced axle pivot arc allowed the use of simple rubber flex joints at the outboard ends of the drive shafts in lieu of costly CV joints.
The result was a rear suspension that gave better wheel geometry than the pure swing axle design used on contemporary Volkswagens and Porsches. The reduced camber change was almost on par with the Mercedes-Benz single low-pivot swing axle design.
The front suspension was no less novel. The upper and lower A-arm design retained the transverse leaf spring (although now acting as the lower A-arm, rather than the upper) used on the 500 Topolino, However, the spring was now fastened to the chassis with rubber bushings at two positions rather than a single centre-mount. In addition to reducing camber change over the range of wheel travel, the twin flexible mountings, located 50 cm (20”) apart, served to coerce the leaf spring to function not only as a springing media, but an anti-roll bar as well. Body lean under cornering forces would cause the centre of the spring to assume a S-shape curve, increasing the effective spring rate at the outboard wheel. This was quite sophisticated at the time. In 1955 anti-roll bars were quite rare in general, and unknown on cars in the price range of the Fiat.
The overall result was a vehicle with superb handling with the playful joie de vivre that recalled the Topolino and would characterize small Fiats for decades to come.
The exterior was a pleasantly shaped two-box affair, with stylized lines suggesting the appearance of separate fenders. This was a common design convention of the time, serving to transition customers to the new monocoque designs which did away with traditional separate fenders. Giacosa himself was at times found personally working on the full-scale plaster mockups. In lieu of a front grille, the 600 had chrome “whiskers” surrounding a central Fiat emblem that incorporated an open surround serving as the horn grille.
The first of what would be many rear-engined Fiats, the 600 made an auspicious debut at the Salon de Genève in April of 1955. The only all-new car at the event; the new 600 was the undisputed star of the show. Fiat added to the festive atmosphere by having thirty staffers continuously drive a fleet of new 600’s through the streets and avenues of Geneva for the duration of the Salon.
The new Fiat received rave press reviews and proved an immediate success. The 600 remained a fixture of the Fiat lineup for fifteen years with comparatively few changes throughout its life. The engine grew from 633 to 767 cc, the doors were reversed to hinge at the leading edge and various exterior and interior trim changes were implemented. Otherwise, the car stayed very close to Giacosa’s original conception.
A year after the introduction of the 600, Fiat released the Multipla, a people-mover version of the car with seating for up to six via three rows of seats, despite being only 25 cm (10”) longer than the sedan and sharing the same wheelbase.
This was accomplished by adopting a forward-control configuration in the manner of the Citroën H and Volkswagen Transporter, with the driver sitting over the front wheels and the pedals and steering wheel located forward of the front axle.
Unlike the aforementioned vehicles, the Multipla was built low to the ground, only 18 cm (7”) taller than the 600 sedan. In a welcome departure from previous forward-control models, the steering column was double-jointed, enabling the wheel to sit at a traditional car-like angle. The Multipla became immensely popular with large families and a favourite for commercial van, ambulance and taxi applications.
A major attraction of the 600 for sporting enthusiasts was that it served as the main canvas for displaying the artistry of Carlo Abarth. Carlo had previously sold performance parts and kits for the Fiat 1100 and built many specials using its underpinnings; but it was the that 600 represented the ultimate fruition of his vision. The 600 became the base for the iconic Fiat Abarth Derivazione 750 and its offspring: the 850 TC, 850 Nürburgring, 1000 TC and numerous carrozzeria-bodied sporting versions, the most famous being the Abarth 750 Zagato.
The most influential of the various Abarths models was without doubt the 750 Berlina sedan and its successors. The 750 Derivazione was the first aftermarket-tuned vehicle sanctioned by its original manufacturer. The 750 was comprehensively modified by Abarth with engine enhancements, revised gearing, chassis improvements and upgraded instrumentation.
The precedent established by Carlo Abarth with the 750 and its progeny was later emulated by Amédée Gordini, John Cooper, Carroll Shelby, Burkard Bovensiepen (Alpina) and Hans Aufrecht & Erhard Melcher (AMG.)
Although Abarth would later apply his talents to other Fiats and some Simcas, none were as fondly embraced as his 600-based models.