A record number of new light vehicles were registered last year, and the net growth in the fleet was the highest since 2005.
Adding to last year's increase was the ongoing decline in the number of old cars being scrapped.
Association figures show the nation's car fleet numbered 2,482,513 at the end of 2013, or 1.46 cars a household.
Mr Stronach said that raised questions about how many cars New Zealand roads could take.
"There won't be any less cars this time next year, in fact there'll probably be another 60,000 to 70,000."
Ministry of Transport statistics show vehicle travel distances increased slightly last year after remaining relatively flat since the mid-2000s.
The New Zealand Transport Agency said the trends and patterns for travel and for congestion were complex and influenced by many factors.
Spokesman Andy Knackstedt said more vehicles did not mean people were not also using other modes of travel, including public transport, walking and cycling.
AA spokesman Mike Noon said cars had become more reliable, so older vehicles continued to run well and hold their value.
But they did not have the safety features of newer cars, such as electronic stability control.
"Some of the early large four-wheel-drives, for instance, have some very nasty handling characteristics," he said.
Imported Motor Vehicle Industry Association chief executive David Vinsen said the growth in the vehicle fleet was related to the rising population, families buying a second or third vehicle, and the time lapse before people got around to disposing an old car.
Mr Vinsen said the average age of cars being scrapped was 20 years, while the average age of a used import was eight years.
Two-car Sainsbury driven by passion
One car enthusiast who has more than one vehicle to his name is former television presenter Mark Sainsbury.
A 1963 Lincoln Continental and a 1971 Bentley Corniche are parked in his Wellington driveway.
"The Lincoln I've always wanted as a kid ... and I finally got it about eight years ago and the Bentley, it turned up through a mechanic I knew and I just fell in love with it. It was such a fantastic car."
The Bentley, which belonged to industrialist Sir James Fletcher and when new "cost more than a house", was rare, with only about 60 made, Mr Sainsbury said.
"Why do I have two? Well, they're different - one's English and one's American."
He uses both equally, and often goes on long road trips, including up to Auckland and around the South Island - as well as trips to the store.
"If you don't use them, that's when you start to get problems."
