The average dealer saw profits rise 4.4% to £118,000 in March compared to the same period last year.
Dealer profitability specialist ASE said the performance was “very creditable” and underlined the resilience of UK motor retailing.
“To improve profits whilst consumers and businesses were faced with the massive Brexit uncertainty we saw during March is a strong result,” said ASE chairman Mike Jones.
Dealers did see a fall in return on investment on used cars, which fell below 80% for the first time since the end of 2016 due to higher stock holdings and reduced stock turn.
But aftersales continued to show “slow and steady” improvement during the plate-change month.
“We have been benefiting from the increased vehicle parc over recent years and this is improving labour efficiency and driving profit. The one area of concern is the high level of warranty content, particularly amongst some brands, depressing retail,” said Jones.
In the first quarter profitability is slightly ahead year on year and the forecast is positive.
“As we move through the remainder of the year we come up against some weaker comparatives, particularly within the brands heavily impacted by WLTP delays. This should leave retailers well placed to outperform their prior year results,” said Jones