Two years ago, industry analysts at Glass's predicted that the average age of vehicles on forecourts would fall, but the new semi-annual registration plate change appears to have accelerated the ageing process.
Chris Smith, editor of Glass's Older Car Guide, said: 'Everybody is so attuned to the old 'one letter per year' registration system that cars now seem to be ageing at twice the speed they used to.
The general effect on the trade has been to shun any vehicles over five years old, other than in exceptional circumstances.'
He added that the abundance of new and re-styled models also influences the trade, and rather than creating a halo effect for the rest of the range, they tend to speed the demise of older cars as the public is attracted to the latest offerings. Glass's also commented on the low interest rates in 1999, and since then they have fallen further, leading to an increased appetite for new cars.
It has also had the effect of drawing business up the age range, says Glass's, leaving many older cars stranded without buyers.
Smith said that with a recession appearing increasingly unlikely, it is difficult to anticipate a change in the situation in the foreseeable future.