The prediction for 2009 is, for the first time, a further decline: 2.325 million, or 10,000 fewer than 2008.
Over the first four months of 2008, registrations kept in step with the corresponding period of 2007 (a nominal drop of 0.04%).
But the SMMT is gloomy about prospects for later in the year because economic factors look likely to depress demand for new cars.
“There are concerns that GDP growth may slow to around half the 2007 level,” said an SMMT economist.
“That, combined with rising cost pressures on both consumers and businesses, has heightened uncertainty that the current robust nature of new car demand will continue.”
Year-on-year, last month was 3.24% higher (5,505 units), the best monthly growth of 2008, and the best April volume since 2005.
One factor was the three additional DVLA processing days because Easter fell in March.
With diesel hitting £1.25 a litre in some places, buyers appeared to be targeting models that would use less fuel.
In April 1,323 alternatively-fuelled vehicles were registered, an 8.4% year-on-year rise, and 14.4% higher year-to-date.
#AM_ART_SPLIT# Paul Everitt, SMMT chief executive, said: “With fuel prices sky high, consumers are looking for motoring they can afford, with a stronger focus on super-efficient small cars.”
SMMT forecasts for 2008 diesel car registrations have risen to 1.005 million (3.9% up, 43% market share), with a further advance expected next year (1.020 million, 1.5% up, 43.9% share).
Diesel cars accounted for a monthly record of 45.4% of the April market with buyers pursuing perceived savings through additional miles to the litre despite the fuel’s price advance over unleaded.
Buyers also have their eyes on next year’s higher vehicle excise duty system and a new fee for first registrations.
Ford is nearly 13,000 units ahead of Vauxhall over the first four months, and showing little sign of giving up its long-running market lead.
But its main challenger was running slightly ahead of the leader in April.
BMW was 25% up over January-April (and by 72% in April), well ahead of Audi (5.41% higher) and Mercedes-Benz (3.70% more registrations).
By contrast Lexus and Porsche were more than 17% down.
A Lexus GB spokesman said: “We are expecting our sales this year to be 10% down on 2007.
This is because we have ended corporate terms to brokers on batches of five to 10 cars to be sold to their local businesses.
In the long term we believe we will benefit by encouraging our retailers to supply firms in their territories.”
A Porsche Cars Great Britain spokesman said: “Consumer confidence is low and we are affected by that along with everyone else.
Also, our sports car range was last updated in 2004, though Cayenne is up year-on-year.”
Top April registrations