Buyers always move to more practical choices in a recession (remember when the 1989-91 recession decimated coupé sales?).
However, this downturn is changing our buying habits more sharply than on any previous occasion.
Whatever criterion you look at, buyers are turning away from the extravagant and impractical towards the frugal and sensible.
For the first time in at least 20 years, both the average engine size and average engine power have reduced over the last two years.
From the beginning of the 1980s until 2007 those figures went up, no matter what the economy was doing.
However, so far this year, they have both turned down with engine size now back to where it was in 2002/2003.
And bhp has fallen from its 2007 peak of 124.7 to 121.2bhp.
In addition, the slow decline of manual transmissions has been reversed.
The share of manuals has risen from 79.6% to 80.7% in the between 2007 and 2009.
Despite the advent of excellent new dual-clutch transmissions, buyers are going back to simple, cheap manuals.
Similarly, the proportion of five-door cars has risen, as what people need takes precedence over what people want.
The proportion of five doors has gone up from 65.6% in 2006 to 69.3% in 2009.
This is sharpest rise that has been seen in at least 25 years. It is simply down to buyers completely re-evaluating their choices.
In fact, the only cost feature to increase its penetration has been diesel, as customers see that as a “spend to save” item.
Buyers believe they will more than get their extra outlay money back in the long-term.
Diesel has passed many milestones so far this year – it has hit 50% penetration in the lower medium segment, the largest sector of all, 80% in upper medium and 90% in executive.
The overall change in attitudes is neatly summarised by comparing the best selling models in pre-recession 2006 with today.
In 2006 the two best sellers were both lower-medium models, followed by two superminis.
Now, superminis are in first and third place while the number of superminis in the top 10 has increased from three to five.
In particular segments, the change has been even more dramatic.
Since the end of 2007, the average engine size of an off-roader has reduced from 2530cc to 2390cc.
Now, that might not sound huge, but it represents a reduction of 5.9% in just over a year.
If the reduction continues at 5% a year, there will be a lot of large off-road designs looking like beached whales.