The government is not giving consumers enough advice on whether they should be buying electric vehicles, according to a leading car industry body.
Stephen Latham of the National Franchised Dealers Association said many people were still confused.
He was speaking on the BBC's Inside Business programme.
In July 2017, the government announced that new diesel and petrol cars and vans would be banned in the UK from 2040 in a bid to tackle air pollution.
The government is under pressure to bring forward this deadline and ban all sales of new petrol and diesel cars by 2032.
It follows a report by a parliamentary committee that described its plans as "vague and unambitious".
"There's some hold-back on new cars because the consumers are genuinely not certain of which direction to jump in," Mr Latham told Inside Business.
"We could do with some clear guidance from the government, because by holding back on the diesel issue, by not saying it's absolutely taboo, we're actually keeping people in older, dirty diesels, instead of them maybe upgrading to the clean Euro 6 diesels, which are available today."
Speaking on the same programme, Caroline Willis from Portadown car dealer Shelbourne Motors, said it was important that the government got behind the move towards electric vehicles, and provided greater information and encouragement to consumers.
Inside Business is broadcast on BBC Radio Ulster on Sundays at 13:30 GMT and on Mondays at 18:30 GMT.