Z Energy is the country's largest fuel retailer and last year acquired a controlling stake in spot power retailer Flick Electric as part of a strategy to use new technologies to help keep ahead of rapidly evolving trends in mobility and retailing.
That has seen the firm take a stake in a car-sharing business and develop an app-based Fastlane service based on camera recognition of licence plates.
Bennetts said he expects to name the firm's new chief digital officer next month. That person will champion a "digital-first" model for the business.
"The CDO will develop and deliver Z's digitisation strategy by transforming Z to a digital and data-driven business that works within an experimental, agile, customer experience and productivity focused execution model," Bennetts said.
Z shares were unchanged at $6.06, having fallen about 19 per cent the past year. The stock jumped last week after the firm raised its March-year earnings outlook on the back of the sharp fall in crude oil prices late last year.
Day, who joined the company in 2013 from Contact Energy, is currently responsible for technology and risk, alongside his finance roles.
Bennetts said Day has opted to leave, given the reduced scope of the CFO role. He departs in May following the conclusion of the company's year-end processes and will be replaced by Lindis Jones, currently Z's corporate general manager.
Bennetts noted the "integral" role Day had played in the firm's development, overseeing its first private placement in the US, six debt raisings in New Zealand, an extensive upgrade of the firm's enterprise management systems, and the 2016 Caltex acquisition.
Bennetts said the finance function Jones will lead will have a greater focus on productivity. He will also retain responsibility for corporate communications from his current role.
Health, safety and environment general manager Hughes gains the insurance and external risk responsibilities currently managed within the CFO role, and the strategy and sustainability activities currently managed by Jones.
Retail general manager Forsyth will depart in April after 20 years in the fuel industry. He will be replaced by Andy Baird, a former BP executive who has been consulting since 2010, including work on Z's brand change that year, development of its store formats and its loyalty programmes.
Bennetts commended Forsyth for the passion he brought to the business and the role he played developing the retail business.
He said Baird brings not only industry experience from the US, Australia and here, but also a "fiercely" competitive spirit and a focus on world-class execution and customer experience.