It may not fit with its traditional glamorous supercar image but, under Fiat’s direction, Italy has become a hotbed of diesel car manufacture. Guy Baker reports.

Mention diesel engines to most people and chances are their thoughts will immediately turn to German or perhaps French cars.

After all Rudolf Diesel was himself German, the first diesel truck was made by Daimler-Benz in 1923, and the 1933 Citroën Rosalie was the first European passenger car to possess a diesel engine.

And of course today Volkswagen Group, Ford, PSA Peugeot Citroën, Renault, BMW and Mercedes-Benz produce some of the most popular diesel-powered motors on sale in the UK, so it’s really not that surprising. But whilst the rise and rise of the automotive diesel engine is a story of great achievement, there is also a strong Italian connection.

The Fiat Group in Turin first became involved with diesel engine manufacture as long ago as 1903 when under the umbrella of Fiat Aviazione (now known as Avio S.p.A.), engineers developed diesel powerplants for aviation and marine applications.

In 1909 Fiat San Giorgio was established to produce engines for both submarines and surface ships, and after the First World War, the company started to diversify, producing an increasing number of diesel engines for rail locomotives.

Much of this growing expertise was employed in the manufacture of diesel engines for a variety of military vehicles during World War II, including tanks.

After 1945, the Agnelli family lost some of its control in Fiat, at least for a while, but much cross-fertilisation of ideas between different groups within the Fiat family continued, with a truck-based 1901cc diesel engine appearing in the Fiat 1400 range from 1953 – Fiat’s first proper diesel-powered passenger car.

Diesel engine manufacture for motor cars continued alongside Fiat’s maritime and train applications right up until 1959 when Fiat finally decided to move away from diesel engine technology and expand its gas turbine business instead.

At that point the automotive sector was still focused primarily on petrol engine production, and diesel automotive engines took something of a back seat until the 1980s, when a clamour for more efficient automotive engines led Fiat back once again into diesel technology.

This culminated in the launch of the Fiat Croma in 1986 – the first passenger car in the world with a direct-injection turbo-diesel engine.

From that point on, Fiat Group’s diesel engineers have gone from strength to strength, launching the Alfa Romeo 156 in 1997 – the first car to boast a common-rail diesel engine (the JTD or uniJet Turbo Diesel) – the MultiJet JTDm engine in the 2003 Fiat Punto, and in 2009, the latest JTDm MultiJet II engine in the Fiat Punto Evo.

February 2011 saw the debut of a second-generation 138bhp 2.0 JTDM-2 MultiJet diesel engine in the Alfa Giulietta hatchback, alongside the existing 1.6 JTDM-2 (103bhp) and the 2.0 JTDM-2 (168bhp) power units.

This state-of-the-art system employs extremely high injection pressures (around 1600 bar) which are independent of engine revs and the quantity of fuel injected.

The 2.0 JTDM-2 engine, with a variable geometry turbocharger, was further tweaked to meet Euro five emissions requirements when it appeared in the 2011 Alfa Romeo 159, whilst in March 2013, Fiat celebrated the production of their five millionth 1.3 MultiJet engine, at their Powertrain Technologies Bielsko-Biala plant in Poland.

This smallest of Fiat diesel engines now comes in three different versions, one with a fixed geometry turbocharger and two with variable geometry units.

Diesel engines have now become a fundamental building block of both the Fiat and Alfa Romeo brands, with Fiat-funded production facilities all around the globe. Fiat has also become very successful at selling its expertise to others, with nearly 100 different models from a variety of manufacturers carrying Fiat-based powerplants under their bonnet.

And Alfa Romeo can rightly claim to have produced some of the finest-looking diesel models ever made. So next time someone mentions diesel engines, don’t jump to conclusions – it could well be Italian.

Guy Baker