The other day I got a phone call from a friend who already owns quite a collection of motor cars.

He wanted to know whether the new Mercedes C63 AMG Coupe Black Series that’s been offered to him (and which we shall be testing next week) is worth what it costs, which is to say £116,000 with one or two choice options fitted.

He also wanted to know if I thought it would make a smart investment or not, what with M-B UK only bringing half a handful of examples into the country during the next few months.

To which I replied: “Sorry mate but the most honest answer I can give you right now is… I don’t know.”

For although I’ve not driven it yet, colleagues who have say the C63 Black is quite some piece of work; a far more convincing effort than its strangely rubbish cousins, the SLK and SL65 Blacks from a year or two back.

But even if it IS as fabulous to drive as the only other Black Series car that’s hit the spot (the CLK), I’m still not convinced it could ever be worth quite so much money. Or that in future it will hold its value and become a classic.

Then again, how exactly do you spot a future classic in the first place?

Approximately 99.9 per cent of all the cars we test at Autocar will spiral down in value before making their way eventually – in about 15 years’ time on average – to the crusher. Which makes identifying the ones that will go up in value a bit like trying to deduce which particular grain of rice in your next biryani will be the tastiest.

The golden rules are: if it’s a limited-edition Ferrari you might just have a quarter of half a chance of an increase in value in the long run – otherwise though, and speaking generally, don’t even go there.

Even bricks and mortar are looking distinctly flakey at the moment, which renders the idea of making money by speculating on cars look very wobbly indeed.

None of which will prevent us from enjoying the C63 Black next week. Neither will it stand in the way of my mate – who has lots of sense but lots of money too – ignoring my advice and writing the cheque. And then defying all logic and making a few quid into the bargain.