Motorists are buying smaller cars in the face of higher fuel prices and road tax.
New registrations of 4x4s last month dipped by 18% compared with May 2007, according to the Society of Motor Manufacturers and Traders (SMMT).
In contrast, supermini sales rose by 120% last month, highlighting that car buyers could be becoming more conscious of their cars' running costs. Diesel sales rose by 8.4% in the same period, too.
Overall, car sales dipped by 3.5% from April.