Car manufacturers will be able to offer customers the same number of diesel as petrol engines for each vehicle within five years, further enhancing the desirability of diesel models, Ricardo Consulting Engineers said today.

The company said that European vehicle manufacturers have significantly increased the development effort directed towards diesel technology, which has led to rapid advances in refinement and performance of today's modern diesel engines.

Common rail fuel injection systems, first introduced in 1997, are now used on the majority of new diesel engine designs. Thanks to better understanding of cooling strategies, improved fuel injection and more advanced turbocharger technology, production diesel engines are now available with power outputs up to 180kW (240bhp).

Ricardo describes the development of mild hybrid diesel engines as “a major future technology, which will help carmakers meet the latest [EC] 140g/km CO2 target.”

The company is collaboratiing with Valeo on a major research project known as i-MoGen (Intelligent Motor Generator) aimed at producing a mild hybrid diesel next-generation prototype, which can demonstrate less than 4-litres per 100km fuel consumption.

The i-MoGen C-class demonstrator's electrical machine accounts for no more than 10 percent of the engine's power output (hence mild hybrid) and uses a 1.2-litre high output diesel engine producing 62kW (83bhp) per litre.

The combination of the downsized diesel engine together with the low speed torque boost of its electrical machine will help i-MoGen achieve a performance feel similar to existing two-litre turbo diesel cars, but with the benefit of even lower fuel consumption and CO2 emissions.