September has heralded huge demand in the auction halls around the country says BCA, as some dealers and car supermarkets are struggling to maintain their retail stock levels.

BCA says it has seen conversion rates ‘rocket’ as professional buyers compete for stock. In the early days of September, the sold ratio hit 87% across the board - not unknown at the busiest times of the year, but still exceptionally high.

BCA’s UK operations director Simon Henstock said: "There are a number of factors combining to deliver these high conversion rates. Motor retailers are telling us that demand for used cars is high, but stocks are thin on the ground."

"The slow new car retail market is not generating the volume of part-exchanges that might have been expected, so more of these are staying on the retail pitch rather than being churned in the wholesale market – further exacerbating the shortfall.

"The orders for new-registration vehicles placed by leasing companies and business users haven’t yet got through the system, so there is also shortage of corporate stock.

"We expect supply and demand to balance somewhat in October and November, but in the meantime if anyone is sitting on supplies of used cars wondering what to do with them, get them in the market and sold. It rarely gets much better than this.”

Price performance has also improved markedly, with most sectors of the used car market seeing values rise - particularly true of niche models.

Henstock said: "What these levels of demand do is turn certain models from great to exceptional RV performers, simply because everyone wants them.

"Mini, for example, has always been a strong performer since launch, but current values are stratospheric. One-year-old Mini Cooper Convertibles are averaging £17,250 – that’s nearly £2,000 above list price, while 0252 Mini Coopers are averaging £10,350 at 35,000 miles – that is equivalent to retail value."

The new Honda Civic i-Shift hatchbacks, BCA says, are also averaging near to list price, while 05 55-model Civic Executives are selling for £1,500 over CAP Clean.

"Small hatchbacks remain popular as highlighted by the Peugeot 206 Verve 5 door model, which is averaging £850 over CAP Clean at 11,000 miles on an 05 55-plate.

"Diesel product is incredibly desirable across the board and at all ages and mileages. We are seeing 05-registered BMW 320D saloons making £1,000 over CAP Clean, and one year old Ford Focus TDCi Ghia hatchbacks are £1,100 ahead of guide prices. Citroen C5 110 HDi estates are averaging 115% of CAP Clean on 0303-plates," Henstock said.

"And while values for convertibles and tin-tops have settled down after a summer which saw them outstripping guide prices, the new Vauxhall Twin Top is currently selling for about £1,500 over CAP Clean – huge demand and limited stock have combined to make values soar."