The Hagerty Blue Chip classic car index has revealed that leading classic car values grew by 13.4% between December 2011 and December 2012.

The index, which follows the price performance of 25 of the most sought after collectible post-war cars, indicates that 2012 has been another strong year for the top end of the sector, building upon gains in previous years.

The 1974 Iso Grifo SII: up 17% between August and December 2012

However, the market witnessed a slight slow down towards the end of the year, posting just a 2% gain in value between August and December.

Hagerty stresses that this could, in fact, be a positive sign.

"Many observers were questioning whether or not another bubble was forming, and 20% sustained annual gains certainly could lead one to that conclusion," says the company's David Kinney.

"This slight slow down shows measured rather than speculative growth at the top of the market, and that is better for the long run. Our Blue Chippers are still at an all-time high, and are still 41% ahead of three years ago."

Of the 25 cars in the index, the 1974 Iso Grifo SII was the best performer between August and December, rising 17% in value.

Other strong showings were seen from the Porsche 911 Carrera RS, Shelby Cobra 289 and Ferrari 275 GTB/4, which were all up 7%.

The only negative among the 25 was the 1953 Chevrolet Corvette, which fell in price by 2%.

For more information check out our Paul Fraser Collectibles' classic car investment guide.

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