Porsche's withdrawal from the World Endurance Championship ended a great period for sportscar racing. Some of the battles against Toyota and Audi between 2014-17 were epic, and Porsche's exit - following that of Audi - put the championship at a crossroads.

Dissatisfaction with future regulations, which Porsche felt "simplified" the high-tech hybrid class, and a new focus on its Formula E entry in 2019-20, contributed to that decision. But that wasn't the end of the 919's story, which includes three drivers' titles, three manufacturers' crowns and a trio of Le Mans 24 Hours successes.

Despite not racing, the 919 has made headlines in 2018 - perhaps more than any other sportscar story, with the exception of Fernando Alonso's ultimately successful Le Mans bid - with two laps, one at Spa and one at the Nurburgring Nordschleife.

In April, works driver Neel Jani recorded a Formula 1-beating 1m41.770s at the Belgian Grand Prix venue, while in June Timo Bernhard went around the fearsome Nurburgring quicker than anyone ever: 5m19.546s.

Those runs, along with appearances at Brands Hatch and Laguna Seca, were part of a 919 farewell tour conducted by a special version: the 919 Evo.

In some ways the car is a throwback to a time of fewer rules restrictions, while in others it is a glimpse of the future, a hint of just how far hybrid technology can go. Porsche recently decided to reveal all (well, nearly all) about the project and invited Autosport to its Weissach base.

The camouflaged 919 prototype catches the eye when Autosport is allowed in to Porsche's LMP1 nerve centre, but there is still an element of secrecy. Our phone is confiscated in order for the camera to be covered up.

Inside, the 919 Hybrid Evo's elements are stripped down to the most minute detail - alongside its racing predecessor. At the same time, the 'real' Evo is on its way to Laguna for the Porsche Rennsport Reunion, its final outing before the car takes its place in Porsche's museum via a drive on Stuttgart's public roads.

Perhaps the first thing to point out about a car that has pushed motorsport engineering limits is that it was Porsche's media and marketing team that made the Evo project possible.

"The idea came shortly after we stopped the LMP1 programme," explains Porsche's LMP1 boss Andreas Seidl. "We had a discussion with our PR and marketing team and the idea was born to do a classic farewell tour."

Porsche has history in this respect and it was its own Talladega closed-course land speed record-breaking run with Penske and the fearsome 917/30 in 1975 with Mark Donohue that inspired the manufacturer's tour.

"One of the ideas was a record attempt, comparing it to stuff done in the 1970s by Penske," confirms Seidl. "I was a bit sceptical at the beginning, as there is risk in these records. But the idea was so convincing that we said, 'OK, if we can find the budget lets go for it'."

That was Porsche's first stumbling block. Why pile boatloads of cash into an existing car - that in its active life had reached Formula 1 proportions of budget in the WEC - in order to beat several records for some PR goodwill? Unsurprisingly, this thought had crossed the finance department's mind too.

In short, Porsche was given a budget that Seidl describes as "very low" and it was topped up significantly by Porsche's many sponsors and supporters.

Although there were developments planned for its never-to-be-raced 2018 LMP1 car, several team members point to the fact that some of the ideas were never made as physical parts. But for the record runs, Porsche was able to scrap elements such as air conditioning, light systems and the pneumatic jack system to further save weight - losing a total of 39kg.

Yet one of the most incredible aspects of the 919 Hybrid Evo is the fact that it is hardly a departure from its predecessor. It was instead about maximising elements such as the V4 engine to its peak performance and developing existing areas to withstand a more extreme level of power, downforce and grip.

Chief race engineer Stephen Mitas describes the Evo as an "engineer's dream come true", but adds that it did not "fully exploit the technical potential". There were still time and money restraints.

Nevertheless, the resulting machine had an entirely new level of performance. On the 'super' Porsche's first visit to Spa, the plan was to shake the car down and get an idea of its performance for its proper record bid.

In hours of discussion about the Evo's records, it's almost alarming how often engineers mention that the Spa record run was not the limit of the car

"In the beginning we had three days at Spa, and as I understand it the aim was always to see [how it worked] and check the car and then come back at a later stage to try and actually go quick," says Jani.

But straight out of the box, the Evo smashed the 919 Hybrid's qualifying time at Spa - 1m54.097s - by 12 seconds. Jani's best mark was 0.783s quicker than Lewis Hamilton's pole lap for the 2017 Belgian Grand Prix, in the dominant Mercedes W08 package, setting a new unofficial record of the Spa circuit.

Sebastian Vettel took the record back for F1 with a time of 1m41.501s in August, but the Porsche mark would stil have been good enough for fourth in Belgian GP qualifying this year.

The grip was a "new dimension" for Jani as Michelin compared the entire lap's tyre demands to the "peak" it has when on the run up Eau Rouge.

While Jani could enjoy a car that pushed him beyond his limits, Porsche did lose time with a Spa-specific struggle due to its movable skirts, which made front-end balance more difficult to find.

"I wasn't locking wheels, there's just so much downforce, grip and braking power you leave marks on the ground without locking up" Neel Jani

In hours of discussion about the Evo's records, it's almost alarming how often the Porsche engineers mention that the record run was not the limit of the car. Aero specialist Matthew Jacquemont points to changing temperatures that prevented the Evo maximising its new aerokit, and the fact that Porsche decided to end its Spa trips after the record run, rather than come back as planned for a 'real' attempt.

Michelin and Jani both felt the tyre was running on high pressures in a conservative approach for safety, which also hindered performance. "We didn't manage to get everything together between track temperature, air temperature, tyres and the skirt," says Jacquemont. "I think we could have been a little quicker. We were quite happy with the lap time, but at Spa we finished the test thinking there could have been a little more..."

But in other aspects, Porsche was pushing the car to its limits, particularly in cooling, which restricted the Evo to short runs, and dramatic tyre drop off, a deliberate factor Michelin implemented for safety reasons.

So incredible was the run, that in a lengthy interview with Jani it was hard to pick out the most mind-boggling aspect of his run, but it was probably his run to La Source.

"Braking for La Source it was amazing," enthuses Jani. "I arrived at around 285km/h (175mph) on the straight, you brake at the 100m board and actually people watching from the outside said from braking you could see the dark tyre marks and rubber on the ground.

"I wasn't locking the wheels, it's just so much downforce and grip and braking power that you left black marks on the ground without locking up."

That wasn't the case at the Nordschleife, a totally different ball game on a lap which is is three times longer than Spa. Timo Bernhard avoided using the kerbs and spent swathes of time learning how to approach a lap in such an extreme car. There's no such thing as a reference point in a record run, only intense preparation on the simulator to avoid errors such as deploying an electrical boost over a bump or crest and unsettling the car.

"The Nurburgring Nordschleife is the toughest track," says Porsche consultant Georg v. Tardy. "For one, the compressions and shocks you have, and the risk because it has no space.

"As we weren't running for 24 hours we built in safety fatigue [particularly on suspension] so we did not have to modify everything. If we had run Le Mans or a 24-hour race on the Nurburgring we would have had to change a lot more. After that, we would have had to trash the parts."

Such was the stress on the car, Michael Engelmeier - tasked with the 919 Evo's cooling aspects - knew that they were restricted to two laps per run. If temperatures got too hot Porsche would also have had to turn down the engine to complete the run.

Eight years earlier Porsche had taken another space-age car to Germany's most famous circuit, with its first hybrid racing car, the 911 GT3 R Hybrid, leading 22 hours of the Nurburgring 24 Hours. Porsche has come a long way since then, underlining the strides that have been made when it comes to combining internal combustion and electric power.

For an idea of how different those runs would likely be, Bernhard compares a more conventional car's approach compared to the Evo.

"One of the most spectacular sections was up the hill out of Kesselchen," he says. "We accelerated out with boost and the long-triple left-hander was flat with DRS closed. Just after that we opened the DRS for the left-hand kink, flat, and then boosted up to 340km/h (210mph) up the hill.

"A street car would get to maybe 100km/h (62mph) and you feel the true power [in the Evo] with the DRS and boost."

Moments later, he had another mind-blowing moment in the car: "Up to Pflanzgarten 1 and [you drive] to a little jump. It was crucial for the car not to jump. I think the front wheels lifted a little bit."

There can be little doubt the 919 Evo is a fitting tribute to the successful 919. One feature of Autosport's visit was some of the engineers' stories of the car. Knowing the journey was coming to an end, one snuck away into the Bahrain grandstand at the 2017 WEC finale to see the 919 Hybrid pushed to its limits one last time in the six-hour race.

It was the sort of misty-eyed tale that proved revealing, with others talking about moments from the 919 Hybrid's history that had not been mentioned before, such as the early teething problems with the original car.

In the space of seven years, beginning with five employees studying new-age powertrains while WEC/Le Mans organisers the FIA and the Automobile Club de l'Ouest worked on what would become LMP1 regulations, the 919 Hybrid grew out of what looked like a building site, pushed to the outer fringes of the enormous Weissach facility. As the project quickly grew to 260 people, Porsche's expectations remained daunting through the following year.

There were some early wobbles, such as a fundamental problem with its gearbox-to-engine shaft that snapped the instant the clutch was pressed when starting the V4 engine. Once that was addressed, there was a bizarre vibration from the engine that perfectly matched the human body's natural frequency and ended up causing breathing and eye problems.

The first season in 2014 was promising, even though Toyota won the championship and Audi took Le Mans. But Mark Webber's serious crash in Brazil caused concern, the electrical charge of the car worrying Porsche that an inexperienced marshal could be put at risk.

Ultimately, though, the 919 more than achieved its goals, with Porsche's Le Mans victory tally of 19 now being six clear of Audi. It seems a shame to retire the Evo when it could still stake a claim to being the fastest car in the world. Is there not a temptation to go back to Spa to take back the record from Vettel?

"No, the run was a one-off," says Seidl. "In the end it was about records as well, but even more we wanted to show what a modern hybrid sportscar can do in terms of performance. We set targets for lap times and tracks we wanted to go and we hit those targets. That's it, no temptation to go back."

Despite the obvious overtaking and stamina issues it would create, could the 919 Evo provide a template for what a modern day sportscar should be as the WEC does some soul-searching with its hypercar concept?

There was an air of sadness from Porsche staff as it said goodbye to the extreme version of the LMP1 machine it began work on in 2013

"Definitely," says Seidl. "It's very encouraging to see this big echo we got from the fans and the internet. It shows enough people like raw, unlimited performance on a traditional race track."

Siedl's last two responses came as Autosport tried in vain for the 919 Evo to be more than a museum item, although the Porsche supremo sidestepped the questions well. But he did quite rightly point to its legacy continuing. It won't be in a record-breaking monster though and it'll certainly be a bit quieter on track.

Through the tour of the nerve centre, it was notable that there were several secretive-looking boxes labelled Formula E.

No, Porsche did not have a Gen2 car sitting ready to go for its impending move to the all-electric series. But depending on your motorsport perspective, it's either a damning sign of the times or a major manufacturer sensing the winds of change and throwing its chips into the electric revolution.

The 919 is now a museum piece, but that does not mean it is irrelevant.

"There is a lot of carryover, not just from the Evo, but from the 919 Hybrid," explains Seidl. "Everything we have learned on the hybrid system side, the gearbox side, the suspension side - as there is some area for development in the rear axle of suspension.

"We are using the same guys for Formula E. There is a lot of carryover."

With the arrival of Formula E's dramatic Gen2 car, development becomes more open, the very aspect that attracted Porsche to enter in 2019/20. Able to design its own electric powertrain and use the knowledge of the LMP1 car's own system in its development, Porsche has found its moment to join the increasingly fierce manufacturer battleground.

Porsche can extend that database of alternative power into an electric motor, inverter, brake-by-wire system and other areas such as the rear-axle, cooling and the ECU.

There was an air of sadness from Porsche staff as it said goodbye to the extreme version of the LMP1 machine it began work on in 2013. Formula E may not be as glamorous as the record-breaking car, but it could turn out to be the 919's real legacy.