Britain’s revitalised national motor show has lost a major supporter with a surprise decision by BMW not to back this summer’s event.

Two years ago, the premium German brand spent £2.5 million on lavish waterside stand facilities at the inaugural ExCel exhibition.

But a review of this year’s marketing budget has concluded that BMW UK is able to spend the cash more effectively elsewhere, AM can reveal.

"We were keen to back what we felt was an important initiative when the show went to the Docklands but circumstances change. What it all comes down to is money – and it’s a fact that we could easily spend 20 times the amount we have at our disposal," said corporate communications director Chris Willows.

Speaking during a visit to the Geneva Motor Show, SMMT chief executive Paul Everitt said: "Naturally, we are disappointed at the way this decision has gone, particularly as VW brands – with the exception of Seat – have again decided that this major fixture on the international show circuit is not for them.

"But other brands take the view that the show works for them. We have signed up Mini alongside significant marques like Vauxhall and Nissan and marques like Fiat, Ferrari, Suzuki and Subaru will be at the event.

"I admit I would prefer to have greater brand representation, but we do have a strong list of exhibitors and 85 per cent of stand space has already been sold. I’m confident the event will achieve greater success this year."

Everitt’s frustration at the no-shows is shared by General Motors Europe vice president sales and marketing Jonathan Browning. Vauxhall unveiled the new Corsa at the last show in 2006 and will be showing the Vectra replacement Insignia for the first time at the July show.

But Browning said: "I am disappointed that the rest of the industry is not getting behind the show."

The 2006 show attracted 415,000 visitors and organisers aim to achieve a 500,000 attendance total this year.