If I wrote that an average who bought the most efficient Volkswagen Golf would need to keep it more than 11 years to get their money's worth, would you think I'd gone mad?

Well that's the truth of it. I spent a few minutes with a calculator and it turns out that you'd need to drive the Golf BlueMotion almost 93,000 miles to have gained any financial benefit from its extra fuel economy compared to an 'ordinary' diesel Golf.

The BlueMotion gives 14mpg more than the 1.6 TDI S model on which it is based, according to official lab-tested figures. Sounds like a lot, but over an average 8,000 miles (a figure that has fallen in recent years) it only works out at £104.59 cheaper per year.

When you consider than the BlueMotion costs £1,215 more than the diesel S, that's 11.6 years you'd need to wait to get your money back. Madness. Even drivers who cover 20,000 miles per year would need to use it more than for four and a half years just to break even on the purchase price! What sort of nutcase have you got to be?

If you know someone who has bought a BlueMotion… please tell them what a colossal berk they've been."

 

There are no road tax implications, either: the ordinary Golf escapes road tax just like the BlueMotion car does, so if you're searching for mitigating financial circumstances you can forget that one.

The Golf is a really, really good car if you buy the right one. If you know someone who has bought a BlueMotion and doesn't plan to keep it until it starts appearing in classic car magazines, please tell them what a colossal berk they've been.

VW Golf BlueMotion

Volkswagen isn't the only offender in terms of building completely pointless eco-specials. Ford is at it too, with the Focus Edge Econetic 88g; so named for its CO2 output.

You can buy one of those, thinking that its 83.1mpg will see you right against a standard diesel Focus Edge's 67.3mpg, but you're looking at a seven-and-a-half-year wait to get your money back – a time span shortened from nine years by the normal Focus' £20 per year road tax liability.

What's more, this is all assuming that the particular eco-banana that you're driving actually matches the claimed relative efficiency increases over their non-eco siblings. Which, more often than not, they don't.

It's a ridiculous set of numbers to read, and when you consider that these numbers are a best-case scenario you might wonder why the devil anyone buys these things. Answers on a postcard...