Diesel sales continued to fall but still had a 39% market share in the month, down from 49% as sales fell 30% to just over 62,000, down 15% in the year to date.
The UK auto recession skidded on last month amid continued soft business and consumer confidence. Elsewhere, BMW's 4 Series has shot into the top ten for the very first time this year, while Mercedes continues to make its presence felt thanks to the A-Class, while the C-Class retains its position of number eight in the year-to-date.
Hawes called for consumers to be given reassurance that the latest, low-emission diesel cars on sale will not face any bans or charges in the UK.
Meanwhile, petrol registrations were up by 2.7% during the same period, while cars known as Alternative Fuel Vehicles, or AFVs - mostly hybrids and electric cars - shot up by a massive 36.9%. "Modern Euro 6 diesel cars can not be compared to older diesel models".
However, Mike Hawes, the chief executive of the Society of Motor Manufacturers and Traders (SMMT), said diesel was getting an unnecessarily bad name and urged action from the government.
United Kingdom new vehicle market sees a sharp drop with demand falling 12% in October as confidence continues to ebb among buyers. Dealers reported 10% fewer private buyers taking delivery of new cars in October. This aligns with SMMT's latest forecast for 2017, published last week, with the market expected to end the year on 2.565 million units - a -4.7% decline.
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"Consumers are showing huge interest in eco-friendly cars and it's reflected in new registrations".
Simon Benson, director of motoring services at AA Cars, comments: "The Government's ongoing crackdown on older "dirty diesel" has had a significant impact on the new vehicle market, with sales plummeting by nearly 30% in October".
"Looking beyond that the uncertainties still facing the UK economy make it hard to make a robust forecast for 2018 as a whole, however the determinants such as UK GDP and employment levels remain robust".
In particular, the data indicates that diesel vehicle sales have seen a significant drop when compared to the same period in 2017, with registrations having fallen by almost a third (29.9%).
General uncertainty is making businesses and consumers reluctant to make buying decisions, according to Andy Hartley, commercial director at Lex Autolease.