MANUFACTURERS of executive cars are anticipating a significant rise in fleet demand for diesel models as company car drivers begin to appreciate the tax implications of the 1999 Budget. The combination of the fiscal phase-out of free fuel for private motoring with a proposed company car tax regime based on carbon dioxide emissions, has played into the hands of diesel.

Historically, diesel's lack of refinement has restricted its penetration into the prestige and luxury car sectors, where image has played a far more important role than budget. But diesel technology has advanced massively with the advent of direct injection and common rail engines which, coupled with improvements in sound-proofing, have made the best examples difficult to differentiate from their petrol equivalents.

Manufacturers insist this does not sound the death knell of so-called 'gas-guzzlers', saying that some drivers will pay the price to drive the car they want, regardless of the tax and fuel duty implications. Yet among middle to senior management the opportunity to save more than £1,000 per year, net of tax, is sure to focus more minds on the diesel option.

Alan Waldie, BMW's corporate operations manager, said: 'I expect our diesel sales to increase, but I'm not sure how much of it is due to the Budget, and how much is due to the exciting new products we have to offer.' Mercedes, too, is seeing strong up-take of its diesel models, which now account for about 27% of E-class sales, while the launch of the A-class has taken the manufacturer into a more budget-conscious area of the UK car market where diesel is likely to secure a growing share of sales.