Car sales across Europe were 10.3% lower in March from a year earlier, the 18th consecutive month of falls.
The figures, from the Association of European Carmakers (Acea) showed most carmakers saw sales drop, with Peugeot Citroen and Toyota suffering the most.
Continuing economic stagnation across Europe has depressed sales for almost six years.
The UK was the only country in Europe where sales rose, with registrations up by 5.9%.
Germany, the best performing economy in the eurozone, saw the biggest fall in sales of 17.1%, with France just behind with a drop of 16.2%.
"The car industry is suffering just as the European economy is suffering," said motor industry analyst Christian Stadler, associate professor of strategic management at Warwick Business School.
The falls came despite hefty incentives on offer to buyers of new cars.
The Reuters news agency said that average retail sales incentives in the top five markets - Germany, the UK, France, Italy and Spain - had risen 13% to almost 2,400 euros (£2,000; $3,200) per vehicle.
Last month, 1.31 million cars were registered in Europe.
Peugeot and Toyota were the worst affected manufacturers, with sales falling more than 16% from a year earlier, Volkswagen also suffered a sharp drop, with sales down 15% and the US carmaker General Motors saw sales fall by 12.8%.
Peugeot has forecast a sales fall of up to 5% this year, although since that guidance was given the chief executive has said that the outlook has worsened.
Jaguar was the only carmaker to see serious gains, with sales up by 21%. Mercedes also saw sales rise. although only by 0.8%.
"There are firms bucking the trend, like Jaguar Land Rover who are positioned well in the emerging markets, and you see that those high-end brands aimed at richer customers are not doing as badly," said Mr Stadler.
"Car firms positioned in this way will be able to avoid the worst of the European slowdown."
In a separate announcement, Toyota, which was a pioneer of petrol-electric hybrid vehicles with its Prius model in 1997, said sales of these and its other hybrid models had now passed five million.
Toyota said it had sold a total 5.125 million hybrid vehicles by the end of March, and they now accounted for 14% of its global sales.