UK registrations fell 2.9 percent to 153,599 in October on continued confusion over future diesel policy, the Society of Motor Manufacturers and Traders (SMMT) said in a statement on Monday.
"Vehicle excise duty upheaval, regulatory changes and confusion over diesel have all made their mark on the market this year," SMMT CEO Mike Hawes said in the statement.
Model changes and backlogs at test houses conducting new emissions certification continued to cause shortages across some brands, the SMMT said.
On Sept. 1, the Worldwide harmonized Light vehicle Test Procedure took effect in the European Union, leading some brands to incentivize sales in August to reduce stocks, which resulted in a 23 percent rise in registrations for that month, but this pulled sales forward, contributing to declines in September and October.
Since the start of last month, automakers in EU markets have only been allowed to sell vehicles that have been certified under the WLTP, with few exceptions.
Diesel sales fell 21 percent in October for a market share of 31.9 percent, while gasoline registrations rose 7.1 percent for a 61.2 percent share of the market, the SMMT said.
Ford was the UK's top-selling brand in September despite a 14 percent drop in sales, followed by Volkswagen brand, which dropped 0.6 percent. Third-placed Mercedes-Benz's volume fell 3.4 percent, ahead of BMW, whose sales gained 2.3 percent. Registrations at No. 5 Vauxhall fell 3.1 percent.
Other losers included Audi (-53 percent), Nissan (-21 percent), Hyundai (-19 percent) and Kia (-8.5 percent).
• Download file, above right, for October UK sales by brand
Monthly sales winners included Jaguar, up 82 percent, Mini, which rose 63 percent, Volvo, up 37 percent and Land Rover up 32 percent. Renault volume rose 27 percent, while Toyota was up 17 percent.
Smaller gainers included Peugeot, up 4.2 percent, Skoda, up 3.1 percent and Seat, which rose 2.8 percent.
Through October, the overall market fell 7.2 percent to 2.06 million.