MORE consumers and businesses prefer to buy cars in Spetember than March, according to the latest analysis by Glass' Market Intelligence Service.

The change in registration plate for new cars is a major draw for potential buyers, with many opting to make their purchase to coincide with the plate changes in March and September.

In the six years since the introduction of the twin plate system, September has been the best selling month on four occasions, a pattern that Glass' predicts is unlikely to change in the near future.

One of the most important factors is that contract hire and personal finance agreements lock car buyers in for a number of years, and this will often govern the timing of future vehicle purchases.

Alan Cole, editorial consultant for Glass', said: "Those who previously bought a new car in August under the old registration plate scheme inevitably find it easier to shift their replacement cycles to September rather than March."

One of the main reasons that the new car market moved to the current twice-yearly plate change in 1999 was to help avoid a disruptive surge in sales in August - the month when the changes were made under the previous system.

August alone typically accounted for around 22 per cent of total annual sales, which meant dealers had to withstand the negative financial impact of an inevitable lull in sales just before the plate change, and then respond to the logistical challenge of satisfying significant pent-up demand once August began.

This annual peak has now been replaced with two separate peaks in March and September, that combined account for between 33 and 35 per cent of total registrations each year.

Mr Cole added: "Buyers clearly still favour a new plate, and so merely shifting to a bi-annual change has predictably failed to lessen the impact on the industry of irregular sales patterns."

Glass' predicts that sales in March 2005 will be a key barometer of the overall health of the UK's new car market.

"Demand for new cars is currently faltering, so retailers will be particularly anxious to see how the predicted uplift in sales during March compares to the same period last year," said Mr Cole.