"I will still have an association with Porsche but I won't be doing any races other than Formula 1, which I think is the sensible thing for me to do because I need to be fully focused," Hartley told The Herald.
"I have a big challenge ahead. I am very aware of that.
"I am going to spend all my energy and time on being fit enough, going into the races fresh, sharp and putting every effort into making this next season work.
"It is a massive opportunity that I have got there."
It is a fine balance for racing drivers to mix the benefits of extra seat time with spreading themselves too thin in terms of race preparation and energy conservation.
Hartley has historically enjoyed racing as much as possible but can see that he needs to rein that in this year and narrow his focus.
"In previous years I have tried to compete in every single race I could," he said.
That plan means he will put on hold his long-standing relationship with Porsche, who helped him resurrect his career after his initial Formula 1 opportunities evaporated. But while he won't be behind the wheel of a Porsche in 2018 Hartley insists the relationship will continue.
"I still have an association with Porsche and being a Le Mans winner you are part of the family."
Hartley is back in New Zealand for a short break, during which time he will get married to long-time partner Sarah, but a reduced race schedule this year won't allow him to get home any more.
"Probably just the same as all the other years, which is Christmas," he said. "There was only one year where I didn't come home and that was just because we couldn't afford the flights back.
"It is quite a big time commitment to come home, especially during the year and getting over the jetlag. There is not a big enough break to justify coming back.
"I very much cherish my time in New Zealand, which is generally a month over this sort of time period, we really make the most of it.
"It is obviously still home but that being said we have made a life for ourselves in Europe – we have been there more than 10 years now."