We know, it feels like most of them are on your regular routes.
The latest official figures show the number of cars on the road went up 0.3% last year, while the average age of cars went up to 7.44 years, two months more than a year ago. Over the last 10 years, the total number grew by 9%, a slower rise than the previous decade's 17%. That presumably reflects the fact that we are pretty much approaching saturation point for cars in the UK.
The SMMT (Society of Motor Manufacturers and Traders) said that this year's increase in age was probably due to the recession. Up to a point. It was mostly due to the scrappage incentive in 2009/2010 which reduced the average age of cars, since when the average has been slowly creeping back up.
One interesting statistic is the reduction in high-CO2 cars because of changes in tax. The proportion of cars emitting over 175 g/km of CO2 has gone down from over 50% in 2000 to under 10% today. If you are thinking of buying any new car over 160 g/km of CO2 today (unless it is a very upmarket or high performance car), bear in mind that in three years it going to be very hard to sell without a massive discount.