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Niki Lauda, who has died aged 70, was a three-time Formula 1 world champion, non-executive chairman of the world champion Mercedes team, and one of the biggest names in motorsport.

He was also a pilot and successful businessman, who set up two airlines and continued to occasionally captain their planes into his late 60s.

But he will be remembered most for the remarkable bravery and resilience he showed in recovering from a fiery crash at the 1976 German Grand Prix at the fearsome Nurburgring.

Lauda - leading the World Championship, having won his first title a year earlier - suffered third-degree burns to his head and face that left him scarred for life, inhaled toxic gases that damaged his lungs, and received the last rites in hospital.

Yet he returned to racing just 40 days later - finishing fourth in the Italian Grand Prix. By the end of the race, his unhealed wounds had soaked his fireproof balaclava in blood. When he tried to remove the balaclava, he found it was stuck to his bandages, and had to resort to ripping it off in one go.

It was one of the bravest acts in the history of sport.

At the time, Lauda played down his condition. Later, in his disarmingly frank autobiography, he admitted he had been so scared he could hardly drive.

"I said then and later that I had conquered my fear quickly and cleanly," Lauda wrote in To Hell And Back. "That was a lie. But it would have been foolish to play into the hands of my rivals by confirming my weakness. At Monza, I was rigid with fear."

Lauda drove that weekend because he felt it was the "best thing" for his physical and mental wellbeing. "Lying in bed ruminating about the 'Ring would have finished me," he said.

The accident ended the notorious Nurburgring's time as a Formula 1 circuit.

Lauda had been warning for some time that the circuit was too dangerous for F1. Its 14 miles twisting through the Eifel mountains meant the emergency services were stretched too far, he said, and any driver who had a serious crash was therefore at a disproportionately high risk in an era that was already extremely dangerous.

What happened on 1 August proved him right. For unknown reasons, Lauda lost control at a flat-out kink before a corner called Bergwerk, hit an embankment and his car burst into flames.

Trapped in the wreckage, but conscious, he was dragged clear by four fellow drivers - but not before he had suffered severe injuries.

Lauda carried the scars, including a mostly missing right ear, for the rest of his life and always had a matter-of-fact approach to his disfigurement. It didn't bother him, he said, and if others felt differently, that was their problem.

His injuries, in fact, were often the butt of his merciless wit.

Once it was pointed out to him that, owing to the rule that says the original start of a race does not count if there is a restart, he had not officially taken part in the 1976 German Grand Prix. "Oh yes," he said, in his clipped tones. "So what happened to my ear?"

The accident came at a time when Lauda appeared to be cruising to a second consecutive world title for Ferrari, and his determination to return was founded in his desire to shore up a lead that was rapidly diminishing in his absence from competition, under assault from British McLaren driver James Hunt.

The compelling narrative of that season was effectively the kick-start for F1's current global popularity. The storyline had something for everyone - the ascetic Austrian racing driver-cum-engineer, renowned for his clinical approach and lack of emotions, driving for Ferrari; the handsome, playboy Englishman bon vivant for McLaren. Lauda's crash and awe-inspiring recovery only added to the frisson.

By the final round in Japan, Lauda was only three points ahead, and when raceday brought torrential rain, he pulled out after two laps, saying it was too dangerous.

Lauda admitted he was "panic-stricken" - feelings rooted in his crash - but later said he regretted the decision. Ferrari remonstrated with him and tried to convince him to race, but he refused, and Hunt took the third place he needed to win the title by one point.

Their battle has been turned into a Hollywood film, but it misrepresented them as enemies - in fact, Lauda and Hunt were close friends. So much so they had next-door rooms that weekend in Japan and, on race morning, with Hunt in bed with a girlfriend, Lauda goose-stepped into the room and barked out: "Today, I vin the Vorld Championship."

Hunt (right) narrowly beat Lauda to the world title in 1976

It was unarguably the most dramatic, inspiring and fascinating part of Lauda's career, but his life was one lived in Technicolor, and remarkable in its entirety.

He was a singular personality, brusque and matter of fact, but with a wicked sense of humour and independent mind.

After success in the lower categories, Lauda bought his way into F1 in 1971, against the wishes of his well-heeled family, by way of a bank loan secured against his life insurance policy, and started his career with March. He needed a second loan to move to BRM two years later. It was the move that made his career.

He impressed team-mate Clay Regazzoni, and when the Swiss was signed by Ferrari for 1974, he recommended Lauda.

The legendary Italian team had been in the doldrums in 1973, but were about to start a strong recovery under the management of the brilliant Luca di Montezemolo. In 1974, Lauda lost out on the title to McLaren's Emerson Fittipaldi only through inexperience, but that was the precursor to dominating in 1975 in the now legendary Ferrari 312T.

After narrowly missing out on the title in 1976, Lauda won again in 1977, despite falling out with Enzo Ferrari, whose lack of support following the Nurburgring crash fatally fractured their relationship.

The atmosphere chilly, amid Lauda's fall-out with the owner and distaste for his new team-mate Carlos Reutemann, Lauda stayed at Ferrari in 1977 only long enough to clinch the title, and pulled out of the final two races before a move to Bernie Ecclestone's Brabham team for 1978.

The Brabham was beautiful to look at, but its Alfa Romeo engine was uncompetitive, and Lauda began to lose interest in F1. At the Canadian Grand Prix, the penultimate race of the 1979 season, he got out of his car part-way through a practice session and told Ecclestone he was retiring, saying he was "bored of driving around in circles".

He returned to Austria to run his airline, Lauda Air, full-time. But just over two years later he was back in F1, tempted out of retirement by McLaren boss Ron Dennis, on a $3m salary - by far the largest in the sport at the time.

Lauda won his third race back - in Long Beach, California - and in 1984 the team were dominant with the new MP4/2, powered by a Porsche engine funded by McLaren's new backer TAG.

Lauda was out-paced by new team-mate Alain Prost but won five races to Prost's seven, most as a result of the Frenchman's bad luck or retirement, and clinched the title by half a point, the closest margin in history.

He stayed for one more year, 1985, when he was uncompetitive but still managed to win in the Netherlands - holding off a charge from Prost - before finally calling it a day for good, aged 36.

Through both his periods in F1, his driving was characterised by elegant stylishness, all economy of effort and fluidity, which matched his belief it was the driver's job to work as hard as possible on the technical aspects of the car, to make it work for him, and let it do the work. It was not spectacular, but it was certainly effective - as proved by Prost himself, and Jackie Stewart, who shared a similar approach and won a further seven titles between them.

The end of Lauda's driving career, though, did not mean the end of his links with F1.

In 1993, Montezemolo offered him a consulting role at Ferrari, though that did not last long into the management of the team's new boss that year - Jean Todt, who went on to mastermind the dominant Michael Schumacher era.

In 2001, Lauda took charge of the Ford-owned Jaguar team, only to be sacked at the end of 2002 along with 70 other key figures when the performance failed to improve.

From then, he largely combined running his new airline Niki - founded in 2003, after the sale of Lauda Air to Austrian Airlines in 1999 - with an analyst's role on the German TV channel RTL's F1 coverage.

But then, in September 2012, he was appointed a non-executive director of the Mercedes F1 team, a decision made by the Mercedes board, who were unhappy at the team's lack of competitiveness under Ross Brawn, and wanted Lauda as an effective spy in the camp.

Along with Brawn, Lauda played a key role in the signing of Lewis Hamilton to replace Schumacher at the end of 2012. And in early 2013, he became a 10% shareholder in Mercedes, at the same time as Toto Wolff took on 30%.

Wolff, initially appointed executive director, replaced Brawn as team boss in 2014, and after that - as Mercedes dominated the sport in the era of turbo hybrid engines - Lauda had attended races and acted as an adviser to Wolff and the Mercedes board.

In July 2018, he was diagnosed with a severe lung infection and had a double lung transplant. In November, he and the team posted a message on social media with a video of Lauda saying he would be back at work "soon".

But in January he was diagnosed with pneumonia and taken back into hospital in Vienna.

Lauda leaves his second wife Birgit, their twins Max and Mia - born in 2009, two sons from his first wife Marlene Knaus - Mathias and Lukas, and a son - Christoph - born from a third relationship.