Alfa Romeo Giulietta 1954

For the first four decades of the marque, Alfa-Romeo had been unremittingly the builder of great sports and racing cars - so great that the 2.9-litre 8C of the late Thirties merited descriptions as, "best car in the world", "ultimate sports car of the pre-war period", and "the modern counterparts of a Rembrandt painting".

No Alfa Romeo had been made in quantity, all were largely built by hand, and annual output had rarely reached 800. This changed in 1950 when they took to mass production with a family saloon that could have been a French Ford or a Fiat.

The 1900, influenced by the clichés of American design, abandoned the coach-built body on a separate chassis - and its sporting heritage - for the doubtful benefits of the monocoque load-bearing body. Suddenly a marque that had always collaborated with Italy's master craftsmen, gave into the demands of standardisation. Not for long; in 1954, Alfa Romeo introduced the Giulietta.

The Giulietta was a lissom little coupe. Designed by Bertone, it was a response to those built by one-man-bands like Cisitalia and Osca, perhaps even to the Volkswagen-based Porsches. But in seating four, it trounced them, for it enabled the family man to pretend that he was a sporting driver. Under the bonnet was a short-stroke Alfa engine; of only 1,290 ccs. This was the smallest twin-camshaft unit to be made in quantity, and in base form developed 80bhp at 6,300rpm and could reach 102mph. Most British cars would have, at such revolutions, thrown their big ends through their engine-blocks.

So freely did this engine respond that it encouraged drivers to cling to lower gears until above 4,000rpm at which it began to emit a thrillingly harsh mechanical note reminiscent of a racing car. Yet it was always smooth and tractable. Within a year the family man got his ideal car when Alfa Romeo installed this engine in the Berlina, a four-door saloon that could reach 100mph. Between 1955 and 1962, it was the first Alfa Romeo with a production total in six figures - 192,917 - few survive, recycled Russian steel of wretched quality their inexorable enemy.

Alfa Romeo again responded to demand when, in 1956, they introduced a Spring Veloce version of the engine. Its capacity was the same, largely by raising the compression ratio from 8:1 to 9.5:1, and changing to twin Weber carburettors and an electric fuel pump, bhp was raised to 95 and 6,000rpm. To put this in an English context, the 3-litre Alvis of the day, a gentlemanly sports car, produced only 104bhp at 4,000rpm. It was then decided that the engine's potential could be further exploited if the cars were even lighter and more aerodynamic.

And between 1959 and 1962 Bertone and Zagato made Sprint coupes that have become classics. Bertone fell back on his fantasy designs for the Berlinetta Aerodynamica Tecnica made for the 1.9-litre chassis of 1950 - now, inevitably, known as Batmobiles; these he tamed a little for the Giulietta, but his redesign still seems fussy to the purist, 1,366 were built. Of the Zagato there were 210 - yet it is a more rational design; only in the wayward cutting of its wheel arches and in the Plexiglas side windows is the purity flawed.

This Coda Tonda (Round Tail) is the most elegant. Made from aluminium, weight-watched (the Morris Minor is marginally heavier), with a higher top gear ratio and the engine tweaked to give 116bhp, it is capable of 120mph. With a fuel tank of some 20 gallons, it promises uninterrupted high-speed motoring.

When the larger Giulia replaced the Giulietta in 1962the coupes were adapted to take the new five-speed gearbox and 1,570cc engine. The Giulietta engine was installed in 144,213 Giulia family saloons as an economy model. Economy, my foot; it struggled with an average weight of 23cwt and proved that a small engine overburdened is always slower and less economical than a larger engine working easily. This is not the model to recall when celebrating the Giulietta's half-centenary.