Major carmakers mounted a concerted campaign of preregistration in the last few days of March to boost first-quarter sales figures. The manufacturers, under attack on pricing and from internet car retailers, believe only a steady diet of good news from the industry can bring real customers back into showrooms.

The official Society of Motor Manufacturers and Traders' figures claim a record 401,996 units for March, an 8.6% increase on the same month last year. Industry sources expected some shift towards the early year plate change, but most were predicting 340,000 to 360,000 units.

Confidential figures obtained by Automotive Management reveal the true pattern of car registration.

The month started well, with registrations in the first seven working days up 8.8% over the same period last year. But then it slumped, down 19.4% in the middle of the month, before the carmakers stepped in to rescue the situation.

Figures show 134,490 cars, just over a third of the total, were registered in the last eight working days of the month. Ford, which claimed the top two places in the chart for its Fiesta and Focus models, registered 22,698 cars in that period but it was not the worst offender.

Fiat registered more than 45% of all its cars in the last five days in a desperate attempt to shore up its market share. Nissan and Honda both exceeded 40%. Even beleaguered Rover stepped into the market, registering nearly 30% of its cars in the last eight days.

The SMMT claimed customers were “continuing to take advantage of the competitive transaction prices and deals currently on offer through the franchised dealer network”. But its own figures show retail customers stayed away in March and the main growth came in fleet and small business registrations, both up around 15,000 units.