You're buying a car. How do you spot a vehicle that is likely to need car breakdown cover? Look at its age? Check reliability reviews? Inspect the mile clock?

Well, one of the first things you might want to check is whether or not the car is a fake. Thankfully, copied cars are not something that many of us are likely to deal with, but in the case of one UK-managed German auction house, the topic has become a hot one.

Coys of Kensington allegedly put a prototype Iso Grifo up for sale in Essen, where it was expected to fetch £200,000.

But the Italian car has come under the scrutiny of automotive experts in both the UK and Germany, who say the car is a fake.

Prof Dr Jorg Elsenbach of the German Iso Bizzarrini Club is one of the highest profile critics of the sale, who said the car was not "true".

German detectives have now initiated an investigation into the auction, which, the auction house claims, did not result in a sale.

The Iso Grifo is considered by many to be the original Italian supercar, built between 1963 and 1974. Despite the Italian connection, the cars were in fact fitted with US V8s, enabling them to hit 70mph in first, then up to 171mph in their uppermost gear.

If the car is real, the owner might expect to be handsomely remunerated: the last month the last Iso Grifo ever built was sold in Florida for $440,000.