The sudden jump comes off the back of increased speculation about rising fuel prices, especially since the price of a barrel of oil has topped $50 (£26.83) a barrel.
As a result, car buyers are considering the more economic models over their petrol counterparts as the price at the pumps hits an average of 87.09 per litre and 84.67p respectively. Compared with October last year, the cost of fuel has risen by more than 11%.
According to Cardata, diesel models currently account for 18% of all privately advertised vehicles on the market. SMMT figures show that new diesel sales have rocketed in past five years from 13.8% in 1999 to a record high 37.2% last month.
The top ten most searched diesel powered models on Cardata.co.uk since the price of oil topped $53 (£28.43) a barrel on October 7 have been:
1. Peugeot 206
2. Renault Clio
3. Ford Focus
4. Ford Mondeo
5. Citroen Xsara Picasso
6. Fiat Punto
7. Vauxhall Astra
8. Renault Megane Scenic
9. Vauxhall Corsa
10. Land Rover Discovery
“Motorists are considering the cost of running their cars more than ever before. Inherent to this is the belief that a diesel will be more economical than petrol to run,” says Cardata spokesperson Andrew Sobell.
“The sudden upward shift once again highlights how people see the cost of fuel immediately hitting their pocket, before considering other costs such as depreciation, insurance or servicing.”