Porsche will build a new LMP1 car for its second year back in top-level sportscar racing next season.
Bosses of the German manufacturer's P1 programme in the World Endurance Championship have revealed that this year's 919 Hybrid is undergoing a complete redesign for next season, which will include producing a new monocoque.
They have stressed, however, that the concept of the car and its hybrid powertrain will not be dramatically altered for season two.
Porsche LMP1 technical director Alex Hitzinger said: "It will be pretty much a new car, and that was the decision from the beginning of the programe.
"It was always the plan that we would do a new tub and redesign the car based on what we'd learned in the first year of racing.
"We are a new design team and we can't be expected to correctly optimise our first design shot."
Porsche team principal Andreas Seidl added that the 2015 car would be "designed from scratch" but would be an "evolution not a revolution" of the existing 919 concept.
The plan is that the new car, which appears likely to retain the 919 type number, will be tested for the first time at the end of this year.
Porsche has also yet to reveal whether it will increase the level of energy retrieval for 2015 and move from the six megajoule class to the higher 8MJ division.
"It is open again and we will evaluate the situation in testing," explained Seidl.
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Toyota will continue into next season with an updated version of the existing TS040 HYBRID with, according to Toyota Motorsport technical director Pascal Vasselon, "no big evolutions".
It has also admitted that it is working on a move to 8MJ, but has yet to make a final decision.
Audi has stated that it will retain its existing concept for its 2015 WEC challenger and that it is trying to increase its level of hybrid power, which can be interpreted as an attempt to move from the two to 4MJ class.