"It's not that Toyota has gone backwards, it's just that Hyundai is irresistible to many buyers," he said.
"They're some of the most reliable cars on the road and they're very practical and come with lots of features and above all else they've finally got their styling together so it's not a car you feel embarrassed about having parked up your driveway."
Overseas, Hyundai targeted the medium to low end of the market but this was not the case in New Zealand.
"A number of your traditional Toyota customers who have brought generations of Corollas have now simply jumped ship."
Matthew-Wilson did not expect Toyota to tolerate the erosion of market share.
"Underestimating Toyota is like underestimating America. When the chips are down they will come through with the goods."
New car sales exceeded expectations in March, led by an increase in the number of new passenger car sales. The number of new vehicles rose 3 per cent to 8528 in March from a year earlier.