The first passenger car to use the diesel Common Rail System was the 1997 Alfa Romeo 156 1.9 JTD.   The 156 (known internally as type 932) was a replacement for the Alfa Romeo 155 and was built at the Fiat Group factory in Pomigliano d’Arco, Italy.

The diesel Common Rail System precisely injects diesel fuel at a very high pressure (much higher than in a gasoline engine).   Its name derives from the one common fuel feed pipe – or rail – that provides fuel for all injectors.  The system reduces exhaust emissions and lowers engine noise, thereby ameliorating the two most common objections to diesel-powered automobiles.

The design work for the Common Rail System had been started at the Fiat Group and was subsequently sold to Robert Bosch for completion and refinement for mass production.

The Alfa was quickly followed by the 1997 Mercedes-Benz C220 CDI.  The C-Class was all new that year and the C220 CDI was the first passenger car with a  turbo diesel engine to use the Common Rail System.  The C220 had significantly better fuel economy, lower emissions, and 30 more horsepower than its predecessor.

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