Vauxhall's dealers are the first to feel the effects of the more open competition envisaged by Trade and Industry Secretary Stephen Byers. They must take a margin cut to match the 'indicated' on-the-road prices announced in last week's 'Vauxhall value pricing' campaign.

The manufacturer claimed its dealers would be able to offer UK sourced cars at “prices comparable to imported vehicles”. The tactic, widely seen as an attempt to pre-empt the Competition Commission report, involved unbundling all consumer finance offers and admitting recommended retail prices were “probably irrelevant”.

Vauxhall gave journalists “an indication of prices that could be offered by participating dealers”. It has not advertised those prices and admitted the selling price of the cars would depend on dealer financial support.

Andrew Andersz, Vauxhall public affairs director, said: “Ultimately, it is up to the dealers what price the cars are advertised at. We don't know how many will participate in the programme. They can be part of this if they put something in as well.”

Industry sources suggested margins would have to fall to below 8% if dealers were to match the 'indicated' prices of Corsa from £6,150 and Astra from £9,999. Vectra is also included in the programme.

Mr Andersz admitted the move could penalise smaller dealers.