Sales in September was the dog that didn't bark. Everyone had been expecting a downturn as the UK economy weakened, but registrations actually grew by 1.3% for the month and 2.0% year-to-date.

There were also expectations that consumers would buy smaller cars as the environmental debate intensified, but that did not really happen (see table).

Indeed sales of city cars declined last month as consumers awaited the new Fiat 500 and Ford Ka, while sales of full-size MPVs have grown, thanks to the storming performance of S-Max.

Meanwhile that green hate-figure, the 4x4, has fared surprisingly well. Despite all the press reports about their imminent demise, market share this year is the second-highest ever at 7.3%.

The SMMT hailed the latest registration figures as evidence that UK consumers are buying a greater number of low-carbon cars. The actual figures were rather less exciting than that might have suggested. Sales of cars emitting up to 120g/km of CO2 grew by 13.8%, but they still only accounted for 102,000 units or 5.3% of the market.

The biggest growth of all (in percentage terms at least) came from Rolls-Royce, whose sales doubled to 129 units year-to-date.

As Lamborghini, Maserati, Bentley and Ferrari also increased sales, there is clearly no green factor at work among the super-rich.

In the mainstream market, the most impressive improvement came from Audi (up 18.2% YTD) which is now selling just over 25% more than Mercedes. Vauxhall has also posted an impressive gain of 9.4% thanks to free availability of the new Corsa.

A small cheer should also go up for Alfa Romeo, whose sales rose by 30% thanks to much happier dealers and some price re-alignments.

At the wrong end of the table, the Korean twins Kia (down 24% YTD) and Hyundai (-20%) are making a very unusual appearance. This is due to the introduction of the Cee’d and i30 rather than a sign of any real problems.

Others suffering from declines are Saab (down 11.2%) and Renault (-10.4%), while Porsche is down 8.6%.

The latter figure really is news – Porsche is now in its second year of decline after a decade of growth, as all its models now face stiffer competition.

Finally, in the “why-bother” category there were further declines for Maybach and Cadillac which declined by 21% to 220 units.

Intriguingly half of Cadillac's total sales this year have come from BLS models registered as fleet sales in the month of September.

Year-on-year registrations by segment

Sales of city cars fell in September, but are up overall this year. 4x4s are down, but their share remains strong at 7.3%.