March accounts for almost a fifth of the year's trade.
UK new car registrations outperformed expectations in March, jumping almost 6% against a year ago, the Society of Motor Manufacturers and Traders (SMMT) has said.
The SMMT said March, when new number plates are released, was typically a strong month for car registrations.
However, the increase this March is well above the almost 2% recorded at the same time last year.
The UK figures defy the EU trend, which remains downwards.
There were 394,806 registrations of cars with the new 13-plate, a 5.9% increase year-on-year, supported by strong demand for private registrations, which rose 7.8%.
Private registrations accounted for 51.7% of the market, followed by fleet (43.5%) and business (4.8%).
Volumes were at their highest since the 2010 Scrappage Incentive Scheme and the increase represents the 13th consecutive month of growth.
The March figures took total registrations for the year-to-date to 605,198, a 7.4% increase on 2012.
It has been the new models and the latest technologies that has been the main reason for attracting the new business
Registrations of petrol-fuelled cars have risen by 12.1% so far in 2013, outselling diesels. This was spurred by growth in the small car and private sector markets, the SMMT reported.
Registrations of alternatively fuelled cars dipped in the month, but rose by 2.9% in the first quarter.