Renault, Volkswagen, and Fiat Chrysler led a 29.8 percent European car sales surge last month, the main regional industry body said, as automakers used discounts to clear inventory ahead of tougher emissions tests.

Registrations across Europe rose to 1.17 million cars, well above usual levels for the slow month of August and the 902,870 achieved in the same month last year, Brussels-based ACEA said on Wednesday.

The tougher new Worldwide Harmonised Light Vehicle Test (WLTP) became mandatory on Sept. 1, forcing carmakers including Renault and Volkswagen to halt deliveries of some model versions that had yet to be re-certified for emissions.

Ahead of the deadline, many boosted financial incentives and registrations of their own new vehicles to be sold on the used car market, analysts have said.

"Some auto manufacturers offered pre‐WLTP vehicles at extremely attractive prices," ACEA said. "As a result, double-digit percentage gains were registered in many EU countries."

The numbers published on Wednesday for the European Union and four European Free Trade Association (EFTA) countries reveal that France's Renault posted the steepest increase in regional sales, with a 56.4 percent gain. Its alliance partner Nissan's sales rose 46.3 percent.

VW Group sales jumped 39.3 percent, while Fiat Chrysler registrations rose 38.9 percent, with sales by its Jeep brand leaping by 158 percent.

Forecasters expect the market surge to be offset by a sales slowdown in the remaining months of the year, in which the August discounters are likely to come off worse.

By contrast, Peugeot maker PSA Group and Japan's Toyota, which both had WTLP-compliant line-ups before the deadline, recorded August sales gains of 17-18 percent.