Demand for new cars was down 14.7% last month compared with May 2019, new figures show.
Some 156,737 new cars were registered in the UK last month, the Society of Motor Manufacturers and Traders (SMMT) said.
That represents an eight-fold increase from May 2020 when retailers were closed, but remains down compared with pre-pandemic levels.
Total registrations over the year to date remain down 29.1% on the average between 2010 and 2019.
Plug-in vehicles have taken a 13.8% share of this year’s new car market, up from 7.2% at this point in 2020.
The most rapid growth is in plug-in hybrids.
SMMT chief executive Mike Hawes said: “With dealerships back open and a brighter, sunnier economic outlook, May’s registrations are as good as could reasonably be expected.
“Increased business confidence is driving the recovery, something that needs to be maintained and translated in private consumer demand as the economy emerges from pandemic support measures.
“Demand for electrified vehicles is helping encourage people into showrooms, but for these technologies to surpass their fossil-fuelled equivalents, a long-term strategy for market transition and infrastructure investment is required.”
Jim Holder, editorial director of magazine and website What Car?, said: “The latest May new car registration figures are another sign the industry is on the road to recovery from the Covid-19 pandemic.
“May was the first full month in 2021 when dealerships across the whole UK were able to remain open, with the industry facing strong pent-up demand from buyers.
“What Car?’s research of 1,920 in-market buyers found 31% of buyers are looking to buy between now and September, resulting in a steady stream of traffic to dealerships.
“With talk of potentially delaying further easing of restrictions, it remains crucial the industry can remain open to buyers.”