"I can't believe we left more than $4m sitting in the car overnight." the Christchurch man, who wants to remain anonymous, said.
He bought a ticket on the spur of the moment from Cashmere Super Dairy, and wrote down the winning numbers on Thursday morning, The Press reported.
"I then realised my ticket was in the car, so went out to check it. When I realised I had a line that matched, I could not believe it.
"I rushed inside and grabbed my wife and we both were shaking with excitement.
Among the family's winnings were $2.5 million in cash, an Aston Martin, an Audi Q7, an apartment and a holiday home.