Difficult trading conditions saw new car transaction prices fall by an average of 1.58% during September compared to August according to data released by independent monitor, CarPriceCheck.com.

The figure means average transaction prices have fallen by 2.27% since the start of August for more than a third of the 4,600 models available on the British market.

September was the biggest month-on-month fall since last February when changes in company car tax legislation helped fuel a price fall of 1.34%.

The most aggressive manufacturers during the month were Renault, Nissan and the troubled Fiat Auto Group.

The cost of buying a Clio, Megane or Laguna from Renault dropped by an average of 1.96%, with Nissan slashing prices by 2.72% on its models and Fiat cutting a similar 2.74% figure on no fewer than 90% of its entire range.

Alfa Romeo followed in the lead of its parent company, Fiat, but cutting prices by 1.56% on its most popular 147 and 156 models. The last time average prices fell in a single month for Alfa was last January.

In August, Britain's 'Big Three' of Ford, Vauxhall and Peugeot had boosted forecourt discounts by an average of 1.6%. Prices continued to fall for Ford and Vauxhall last month (down a further 1.8% and 1.12% respectively) but Peugeot delivered a more restrained 0.18% average increase.

The least price active manufacturers during September were BMW, Volvo and VW.

Steve Evans, chief executive of CarPriceCheck.com, commented: "Although it'll still be a record year, the market is depressed at the moment. Some manufacturers could be about to record a fall in sales of anywhere between 12-20% on last September.

"Dealers are competing more and more on price, which makes it a buyers market. But the fact is, dealers are finding it harder to find consumers who are increasingly willing to look further afield and take their time before committing to buy."