New car sales last month were the highest in September for ten years boosted by the the new ‘64’ number plate. 

Sales were up 5.6pc to 425,861 over the year as the industry reached a new milestone with 31 months of unbroken growth. 

September and March are the months when number plates change. They have traditionally accounted for a third of total annual sales.

March produced an 18pc year on year jump but the Society of Motor Manufacturers and Traders (SMMT) said the more moderate September figure indicated demand is starting to level off.

In the first nine months sales were 9.1pc up at 1.9m with the Ford Fiesta and Focus maintaining their market lead, a slight deceleration from August’s 9.4pc year on year growth.

Demand was "boosted by intensifying confidence in the UK economy, with consumers attracted by a wide range of exciting, increasingly fuel-efficient, new cars", said Mike Hawes, chief executive of the SMMT. 

Cheap finance and discounts are credited with providing a sales stimulus that has seen the UK market consolidate its position as the second biggest for new cars in Europe after Germany. 

“The economic fundamentals still look largely positive for the motor industry”, said Howard Archer of IHS Global Insight. 

However, “low earnings growth could become a constraint for private car sales”, he added, while consumers may be worried by the prospect of Bank of England interest rate hikes. 

Ford no longer builds cars in the UK and attributes its success to paranoia. Mark Ovenden, managing director of the Ford business in the UK, told Car Dealer magazine: "The moment you think you're doing it right is when you start going backwards so we've got to stay completely paranoid."

South Korean manufacturer Hyundai has changed two-thirds of its dealer network in the last four years after setting its sights on raising sales from 28,000 to 100,000.