Among the team's best results was at the beginning of the month in Bahrain where the cars finished second and third. It was first time both cars were on the podium.
Dumas, Jani and Lieb finished second at round seven of the championship while the sister car of Hartley, Bernhard and Webber followed them home after six hours of racing.
Hartley and his co-drivers qualified third and after the lights went out the Kiwi quickly moved into second behind the Toyota. Shortly afterwards Hartley began experiencing brake problems and pitted during a full course yellow flag.
"The first double stint was a bit tricky for me," said Hartley.
"On the opening laps it was great fun and a fair fight with the Toyotas, but then I had a problem with the brake temperatures."
Rejoining the fray, Hartley worked his way back up to third before handing over to Bernhard, who worked his way into the lead after taking advantage of other cars' pit stops. Webber jumped in for the final stint but couldn't catch the sister car due to worn tyres.
Porsche 919 LMP1
This weekend is the last chance for the new cars to make that last, final big step to the top of the podium and end the season on a high with a win. While both sets of drivers would relish the idea of getting Porsche's first LMP1 win after 16 years, as an overall team, being able to grab the first win of the season would be the ultimate prize.
"Of course as a professional race car driver you want to win and beating your teammates is all part of that," said the Kiwi driver.
"It would be nice if our car [No20] could get the first win this year but there's a bigger picture.
"As a team [both Porsche cars] we've come close to getting the first win so everyone will be really trying to do it. At the end of the day it's more important that we [Porsche] get a win this year and so everyone will be hoping one of cars can do it and we'll all be celebrating," said Hartley.
As with all the previous races in the series, this weekend's six-hour endurance is no different. It's all about finding the right balance and compromise of performance, reliability and efficiency. Part of this is getting the right amount of downforce for optimum grip and how much stress to put on the engine to be able to challenge the leaders.
The team has improved and impressed each time the cars have hit the track and Sao Paulo could just be the place where Hartley and company could just grab that elusive win.
The Kiwi is on his first visit to the Brazilian circuit and is unfazed, as one of his career-long strengths is being a fast learner.
"I have never been to Brazil, but I have driven the circuit many times on the simulator and watched it on TV. I think it is a track everyone knows from Formula One on TV.
"I'm quite excited about going there and racing at such a famous venue, and I have the feeling the track should be quite good for our car, our hybrid systems and technology. So far we have been improving at every race.
"I'm optimistic," said Hartley.
