Mr Hubbard, 83, died and his 82-year-old wife, who was driving, suffered fracture injuries.
One witness said the crash happened on a straight and usually safe stretch of road.
At the time of his death, Mr Hubbard's Aorangi Securities was being investigated by the Serious Fraud Office (SFO) after it was placed in statutory management owing investors about $100 million.
Fifty charges laid against Mr Hubbard by the SFO were dropped shortly after his death.
The crash occurred just over a year after the collapse of South Canterbury Finance (SCF), the business Mr Hubbard developed into what was once New Zealand's largest finance company.