More than 60% of new car registrations in April were accounted for by fleets and businesses, according to the latest figures from the SMMT.
New car registrations including private sales as well as fleets were down by more than 7% compared with April 2010, but the new car market was propped up by retail sales due to the scrappage scheme in the first half of last year.
The fleet share of registrations (25-plus vehicles) took a 56% market share in April compared with 48% in April 2010, while business sales (10-24 vehicles plus dealer demonstrators) increased their share to 4.9% from 4.1% for the same month last year.
Registrations of diesel cars took a 52.7% share of April's market compared with 45.5% last year, with the Volkswagen Golf as the best-selling diesel model.
Meanwhile alternative fuel vehicles (hybrid and electric vehicles) increased to 1.4% from 0.9% in April 2010.
The best-selling car overall in April was the Ford Fiesta, with the a range of key fleet favourites making up the top 10.
1 Ford Fiesta 6,755
2 Volkswagen Golf 4,973
3 Vauxhall Astra 4,900
4 Vauxhall Corsa 4,888
5 Ford Focus 4,843
6 Volkswagen Polo 4,524
7 Vauxhall Insignia 3,912
8 Nissan Qashqai 3,738
9 BMW 3 Series 3,133
10 Volkswagen Passat 2,720