Demand for diesel among fleets has grown to its highest share of the market this year as companies search to save drivers tax under the new company car tax regime which comes in next April.

Fleet diesel sales in July were up 35.1% year-on-year to 21% of the market, up from 19% at the start of the year. Diesel sales rose year-on-year in July from 12,848 to 17,359, while petrol sales were just 0.8% higher at 59,932 compared to 59,475 at the same period in 2000.

For the year-to-date, the overall fleet market dropped slightly, down 3.9% to 614,169, but diesel sales are booming, up 20.3% on the same period last year at 126,425, while petrol sales were down by 8.7% to 487,744 from 534,040 at the same period last year.

Most manufacturers offering diesel options are enjoying a booming market, with Ford's diesel sales up 32.8% in July to 3,322 from 2,502 last year.

Volkswagen's diesel sales rocketed by 79% last month to 2,943, while Citroen saw sales jump 108.3% to 1,104, Renault by 158.1% to 1,035 and Audi by 121.7% to 696. For the year-to-date, manufacturers are also showing healthy increases in diesel sales, with Citroen, Audi and BMW posting increases of more than 60%.

Mercedes-Benz saw sales jump 137% in July to 423, up from 178, while Nissan diesel sales in July grew to 376, up from 251, with year-to-date sales up 44.6% to 2,261.

Peugeot went against the trend, with diesel sales in July down 12.7% to 2,686 and year- to-date diesel sales down 2.6% to 24,218.

Steve Lambert, Peugeot fleet marketing manager, said: "The 306 has been on run-out for a while and the 307 has just come to market. We have yet to get the 1.4 and 110bhp diesel engines, so supply is restricted."