Car companies undertake serious economic analyses – indeed, former Ford economist Kate Barker went on to become a member of Bank of England’s monetary policy committee.

When forecasting dem-and, they look at all the economic variables – inflation, unemployment, house prices etc.

However, there is a predictor closer to home – what body styles are people buying?

That might sound facetious, but buyers obviously choose more sports cars in good times and more practical cars in tough times.

Looking at the way the sales mix has shifted over the couple of years does not offer much comfort for either manufacturers or dealers (see table).

Despite all the new product activity, convertibles have lost share this year.

At the same time, coupés have fallen marginally, so there is clearly no substitution going on between the two related bodystyles.

The biggest losers overall so far this year have been 4x4s – possibly the most frivolous body-style of all – while the biggest beneficiaries have been estates. How times change – or possibly how little they change if your perspective is long enough.

Five years ago, estates looked as if they were doomed, squeezed between rising sales of compact MPVs and 4x4s.

There seemed no hope of growth for such an in-between product: not as family-friendly as an MPV and not as aspirational as an off-roader.

Now, an estate looks like a great balancing act – lower profile (literally) than a 4x4, but more dynamic and “lifestyle” than most MPVs.

Indeed, at this rate sales of estates will overtake sales of saloons within a couple of years for the first time ever in the UK.

Volvo used to say that it was unique in styling the estate version first and the saloon later, but now it looks quite prescient.

And what of the 800lb gorilla – the hatchback?

Despite all the proliferation of body styles, its penetration is growing, from 57.4% in 2007 to 57.8% so far this year.

That is the highest penetration since 2003: it seems that when times are tough, we go back to the safe option.

That does not mean that there is no point trying to blend body styles – the S-Max has been a big success as an MPV that trades a little space for much better looks.

However, it does show that any new idea really does have to offer benefits, not just features.

Anyone doubting that should consider the grisly fate of the estate/4x4/MPV Mercedes R-Class.