New car registrations rose by 11.5% in April to 148,793 units, which is the tenth successive monthly increase.
Volumes were up in comparison to a weak 2009 performance, with scrappage accounting for 8% of the total.
Paul Everitt, SMMT chief executive, said: "As our new Government establishes itself, the priority must be sustaining and strengthening the economic recovery with particular focus on encouraging the availability of more and better priced finance for businesses and consumers.
"April was another good month for the UK motor industry with private buyers responding positively, despite the end of the scrappage scheme. There are still difficult months ahead, but the strong start to 2010 has led SMMT to increase its annual forecast to 1.924 million units."