"The decline in demand for diesel cars continues to be of concern and the latest tax changes announced by the government do nothing to encourage consumers to exchange their older diesel vehicles for new lower-emission models", SMMT said.
SMMT chief executive Mike Hawes said: "March's decline is not unexpected given the huge surge in registrations in the same month past year".
The Society of Motor Manufacturers and Traders (SMMT), which conducted the research, said economic and political uncertainty had negatively impacted consumer confidence, as had "confusion over air quality".
Registrations for alternative fuel cars rose 5.7%, but this was not enough to offset the 37% decline in diesel auto registrations.
Ian Gilmartin, head of retail at Barclays corporate banking, said the United Kingdom industry still had some reasons to be cheerful.
Le clip déjanté de Philippe Catherine pour soutenir les Herbiers — CdF
Vous n'avez pas fini de l'entendre! Philippe Katerine veut croire que Les Herbiers seront en finale le 8 mai prochain au Stade de France.
"That evidence would suggest once again that the Government would do well to clarify its position on diesels and to stimulate people into buying newer, cleaner cars".
Auto buyers don't know where to turn amid the ongoing debate about the future of diesel vehicles, an industry expert has said.
"There are many, many hundreds of consumers out there who are running diesel cars, [who] would normally have thought about changing round about now but are reluctant to do so because all they hear is that if they do buy a diesel vehicle, it's not going to be worth anything in a few months' time and so they are hanging fire".
"That way, the one in six drivers (18 per cent) we know are interested in buying an electric in the next two years, have the confidence - finally - to make the change, knowing that there are enough public charging points to support their choice. It's time for change".
Demand for diesel was down almost 40 per cent compared with the same month past year, while alternatively fuelled vehicles (AVFS) were up 5.7 per cent. Demand for petrol was up 0.5 per cent.
11 personnes soupçonnées de "tournante" placées en garde à vue — Nord
Alertés, les pompiers et la police sont arrivés sur place peu de temps après les faits, et l'adolescente avait été hospitalisée. Elle aurait été victime de ce que l'on appelle une " tournante", plusieurs viols en réunion.
Christopher McGowan said the confusing messages coming from the government had contributed to the struggles of the motor industry.
"This means creating the right economic conditions for all types of consumers to have the confidence to buy new vehicles", he said.
Diesel vehicles are known to emit lower levels of Carbon dioxide than petrol vehicles, thus helping to reduce the impact of transport on climate change, and have therefore enjoyed favourable taxation rates compared to petrol cars.
The new auto market is a vital part of the United Kingdom economy and is often seen as a barometer of consumer and business confidence.
Une belle journée ensoleillée — Météo du jour
Des cumulus inoffensifs se développeront en fin de matinée, ils seront surmontés par moments de bancs de nuages d'altitude. Les températures minimales seront fraîches sous un ciel généralement dégagé, elles iront de 1 à 8 degrés d'est en ouest.