New car registrations have fallen since April, the longest run of decline since 2011, and are down 2 percent year to date, hit by uncertainty over Brexit and government plans for customers to switch away from diesel and petrol models.

Earlier this year Lookers, which posted an 18 percent rise in first-half adjusted pre-tax profits from continuing operations to 50.2 million pounds on Wednesday, said it expected demand in 2017 to match the record high of 2.69 million sales seen in 2016.

But on Wednesday chief executive Andy Bruce told Reuters the firm had downgraded expectations as the market performed more weakly than anticipated, hit by June's snap general election and uncertainty caused by Brexit.

"We think in the full year the market will be down about 3 percent which would imply a decline in the second half of something between 5 and 6 percent. It's definitely taken the froth off the market," he said.

(Reporting by Costas Pitas, editing by James Davey)