In key fleet sectors such as the upper-medium and junior executive cars, diesel already fuels half of all new company cars.
Dr Manfred Mueller, MD of Bosch's UK Automotive Original Equipment Division, said the expansion of diesel was due to fuel economy, tax benefits and a burgeoning appreciation for the high torque driving characteristics of the modern direct injection diesel engines.
'In mainland Western Europe, where the latest engine technology reaches the consumer earlier and where diesel fuel is significantly cheaper, there is already parity between petrol and diesel, and in some countries diesel is more popular,' he said.
The development of diesel technology is being driven on by the commitment made by Europe's vehicle manufacturers to reduce emissions levels to a fleet average of 140 grams of carbon dioxide (CO2) per kilometre driven by 2008.
'They will only be able to do that with a high percentage of diesels in their portfolios,' said Markus Schmidt, vice president, application and sales, for Bosch's Diesel Systems Division.
'Large powerful cars will remain popular for years to come, but they will almost certainly continue to emit more than the agreed 2008 level. For this reason, vehicle makers will rely heavily on sales of diesels emitting less than 140 g/km of CO2 to redress the balance.
'We will, therefore, continue to see more new diesel models in all sectors of the car market, with particular efforts being made to create one or 1.2-litre diesel engines for small cars.'
The Euro IV emission race