DIESEL-engined vehicles dominate Arriva Automotive Solutions' new Company Car Comparison Guide as the most cost-effective cars to operate over a typical three-year/60,000-mile fleet cycle. The guide takes into account all factors that affect the wholelife cost of a company car.

It shows unequivocally that diesel-engined cars are the cheapest to run in virtually every lease rental category, from £250-£275 per month right up to £600- £650. Arriva's wholelife costs are based on the firm's monthly contract hire rental plus an average annual insurance premium of £500 per vehicle, fuel costs and employer's National Insurance Contributions, minus corporation tax relief. In terms of the fuel cost, the latest Company Car Comparisons Guide has estimated diesel at 73.4 pence per litre, and unleaded petrol at 70.3ppl. Yet this 3ppl discrepancy is more than offset by the vastly superior fuel consumption of diesel cars.

A £13,320 five-door Ford Focus 1.8 Zetec, for example, costs 26.99 ppm to run over three years and 60,000 miles according to Arriva's figures, while the more expensive £13,820 Focus 1.8 TDi Zetec costs 24.98ppm over the same period. Likewise, the five-door Vauxhall Astra Envoy costs £13,525 in 2.0 Di form and returns 25.82ppm, while its 1.6i petrol-powered equivalent costs less at £13,175, but only returns 27.96ppm. The exception is Mitsubishi's direct injection petrol engine which manages to hold its own against diesel equivalents. The £14,695 Carisma 1.8 GLX GDI, for example, returns figures of 27.61ppm, while the £14,935 Carisma TD GLX posts figures of 27.87ppm.

Len Clayton, managing director of Arriva Automotive Solutions, said: 'The percentage of wholelife costs occupied by fuel is going up because of the rapid increase in fuel duty.' He added that this proportion is set to rise further as other wholelife cost elements fall, with new car acquisition prices declining and maintenance bills reducing in line with longer service intervals.