New UK car registrations fell 4.4% in September from a year earlier, according to the motor industry.
That made it the worst September this century in what is normally the industry\'s second most important month.
There were just 328,041 new registrations in the month, said the Society of Motor Manufacturers and Traders (SMMT).
The car sector has been hit hard by the coronavirus pandemic, which closed factories and showrooms.
September is normally second to March as the industry\'s most important sales month, because licence plate changes typically prompt a spike in demand.
But the SMMT said last month saw the lowest volume in new cars since the current licence plate system began in 1999.
\"During a torrid year, the automotive industry has demonstrated incredible resilience, but this is not a recovery,\" said SMMT chief executive Mike Hawes.
\"Unless the pandemic is controlled and economy-wide consumer and business confidence rebuilt, the short-term future looks very challenging indeed.\"