Just 145,377 new cars were registered last month compared to 223,421 in June 2019, according to industry trade body the Society of Motor Manufacturers and Traders (SMMT).
Sales rose from lows of 4,321 in April and 20,247 in May after the government allowed car dealerships to reopen.
But registrations in the first half of 2020 are down 48.5 per cent on the same period last year.
One in five showrooms in England remained shut throughout June while those in Scotland and Wales were not allowed to open until the end of the month.
“While it’s welcome to see demand rise above the rock-bottom levels we saw during lockdown, this is not a recovery and barely a restart,” said Mike Hawes, chief executive of the SMMT.
“Many of June’s registrations could be attributed to customers finally being able to collect their pre-pandemic orders, and appetite for significant spending remains questionable.”
Sales of petrol-engined cars fell 39.9 per cent and diesel-engined sales dropped 59.8 per cent.
Hybrid and electric car sales were one of the few positives in a gloomy set of figures, rising 73.3per cent in June compared with a year earlier.
Despite the rise, three times more petrol and diesel-engined cars were registered than hybrid and electric.
Karen Johnson, head of retail and wholesale at Barclays Corporate Banking, said: “Dealers will now hope that there is a wave of consumer confidence coming down the line, as restrictions on public life begin to be lifted – or at the very least will hope that there is some pent-up demand that might result in increased sales, even if only in the short term.
“Looking ahead, further questions arise around how changing patterns in working environments and consumer attitudes might impact on car sales. On the one hand, many people are working from home and so don’t need a car to get themselves to work every day. Yet on the other hand, people are being advised to stay away from public transport and so may well need their own vehicle to simply get them from A to B.“