March finished with registrations 73% higher than the corresponding month last year, and the industry at odds over its significance.

Market leader Ford faced accusations of forced registrations after Focus leapt to No1, with 20,205 sales. Some industry executives believed as many as 100,000 of last month's 370,060 registrations were not genuine sales. 'Dealer power' was largely responsible for the success of March, according to Cap Motor Research chief economist Mark Cowling, who said many dealers were left to fend for themselves.

He added: “Carmakers channelled marketing spend away from promoting the T-plate and into sales incentives. Dealers were forced to rely on their own innovation. They have been telling us that T-plate suffered from a lack of manufacturer support. Any success is down to their own efforts.”

Mr Cowling believed business sales accounted for what he called the “surprise size” of the first quarter market. “Leasing companies encouraged customers to hold back until the T-plate. A large proportion of the figures are business sales, indicating the strength of the corporate buyer.”

The success of March, however it was achieved, pulled the market back in line with the annual forecast of two million sales after a dismal January and February. The year-to-date figure of 635,942 is a 2.1% increase on the first three months of last year.