On the surface it did not sound like the most challenging assignment: go out and sell a top-of-the-range, flame-red Ferrari 360 - one of the most desirable sports cars on the market. But for some of tonight's contestants on the BBC One show The Apprentice, it proved a challenge too far.

According to television company insiders, some of the would-be young tycoons put up the most farcical business performances yet seen on the show.

Some of them failed to make a single transaction, thus bearing out Sir Alan Sugar's observation that one should never overestimate the limitations of his participants.

“They had one of their most glittering jobs yet - the renting of some of the world's most exclusive cars - but they completely screwed it up,” a source close to the programme-makers, talkbackTHAMES, said.

“Up to now they've been selling boring stuff like ice-cream, tissues and fish - this time it was fantasy stuff. These cars practically sell themselves.

“But they chose the wrong localities and they didn't have a clue what kind of customers to go for. It was astonishing - really poor salesmanship.”

One team apparently misjudged their task so badly that they parked the £110,000 supercar in Portobello Market, West London, between a German sausage stall and a soap stall.

This ignored the most obvious rule of salesmanship: know your market. Shoppers thronging the stalls were unlikely to have either the cash, or appreciate the cachet of such cars. And so it proved.

Their decision also broke the basic rule of The Apprentice, which is that the business created must be capable of being followed through.

And in the case of the eight luxury cars, worth about £2 million in total, one of the conditions was that they could not be hired out to “hawkers or traders”. So, no matter how much ready cash market traders might have, they were barred.

Sir Alan's withering contempt was also aimed at Michael Sophocles, 25, who took his car to Harrods - but parked it down a side street.

In one tragi-comic scene, Sophocles, desperate to clinch a deal, abandoned his car and pursued a man who had shown some interest down the street.

Other contestants proved more able, targeting golf clubs and City brokers, and raising five-figure sums.

There were other amusing behind-the-scenes tensions when the fleet of cars, supplied by Rio Prestige, from Livingston, near Edinburgh, were taken to the scrapyard where filming took place.

Sir Alan rolled up in his Rolls-Royce Phantom, but was displeased to find himself outclassed by the owner of the scrapyard, who told the TV presenter that he not only had a Phantom, but also owned a £200,000 Bentley Flying Spur.

“You could tell Alan Sugar was a bit put out. He didn't hang around after he found that out. When it came to cars, he was competely outclassed,” a source said.

Tonight's episode is the tenth in the present series, with only 6 of the original 16 contestants left in - Michael Sophocles, Lee McQueen, Lucinda Ledgerwood, Claire Young, Helene Speight and Alex Wotherspoon.

Opinions on the ability of the contestants have been varied. The ice-cream entrepreneur who hosted a recent episode was unimpressed.

Alistair Jessel, who runs Farmhouse Ice Cream and Taywell Farm Shop in Goudhurst, Kent, claimed that the wrong team won. “I would have sacked the lot of them,” he said.