In total, 194,955 fleet units were registered last month compared to 171,726 for the same month last year, according to the figures from the Society of Motor Manufacturers and Traders (SMMT). 

The sub-25 “Business” sector also saw a sharp rise, with the figure of 23,209 registrations up 23.4% on the 18,809 recorded for March 2013. Meanwhile private registrations were up 20.8%. 

Overall the new car market was up 17.7% to 464,824 units. The SMMT said that since move to twice-yearly plate change in 1999, only March 2004 saw higher registrations (at 466,954). 

Year-to-date registrations were up 13.7% to 688,122 units, with the fleet sector up 8.7% to 307,193 units from 282,702 units. Meanwhile the sub-25 sector saw an 18.2% rise YtD to 32,971 units from 27,887. The private sector was up 18.1%. 

March is typically the biggest month in year, accounting for almost a fifth of full-year registrations, however the SMMT said the latest figures showed a surprisingly strong level of growth and a reflection of intensifying consumer confidence and the availability of great new products. 

Mike Hawes, SMMT chief executive, said: ‘Given the past six years of subdued economic performance across the UK, there is still a substantial margin of pent-up demand that is contributing to a strong new and used car market. 

'There has never been a better time to buy a new car thanks to attractive finance deals and advanced technologies that often make new cars cheaper to run. We expect the market to continue to perform positively for the rest of the year, albeit at a more modest rate.’