FT.com reported from the Frankfurt motor show that General Motors is unlikely to build a super-luxury Cadillac to compete with BMW's Rolls Royce and DaimlerChrysler's Maybach marques after concluding that there are too many $US250,000-plus vehicles.

According to the report, GM 'product czar Bob Lutz, said the 1,000 horsepower Cadillac Sixteen concept car, shown earlier this year, was unlikely to make it into production in the form originally suggested, in spite of his initial enthusiasm.

He reportedly said the rash of super-luxury vehicles launched recently - including the Rolls, the Maybach and Volkswagen's new Bentley - were all planned at the peak of the dotcom boom and noted that the original Sixteen, on which this year's concept was based, was itself designed in 1928 just before the 1929 stock market crash heralded the great depression.

"I think it is a very limited market and I think it is going to be very difficult for everybody to sell to capacity," Lutz told FT.com.

According to FT.com, Lutz's alert echoes a warning by Bentley chief executive Franz-Josef Paefgen that there were not enough multi-millionaires in the world willing to spend money on the super-luxury marques. Bentley is just about to launch a cheaper model to appeal to people willing to spend around €160,000 on a car, the report added.

FT.com said Lutz did not rule out completely launching a version of the Sixteen as a very low-volume vehicle, saying: "You would want to find a way to make it share a lot of main components with mainstream cars which is the only way you could make it pay off."

FT.com noted that Rolls-Royce and Daimler have dismissed similar concerns voiced by financial analysts - Daimler has sold out the first year of production while Rolls says early sales are good.

GM remains committed to bringing in Cadillacs more expensive than the current range, in an attempt to push the brand - just being re-introduced to Europe - upmarket, FT.com added.