McLaren has won the Formula 1 World Championship at the final round on several occasions, but no victory was as sweet as that achieved by Alain Prost in 1986.

That year the Frenchman was the almost forgotten “third man” in a three-way showdown at the Australian Grand Prix, then held around Adelaide’s fast and demanding street course at the end of the season. And yet the Frenchman beat the odds to pip Williams team-mates Nigel Mansell and Nelson Piquet to the title in one of the most dramatic finales on record.

“It was not only the surprise, it was the way we managed the whole weekend, the whole race,” Prost would recall. “And then at the end, if you have the result, it gives you more fun and more pleasure.”

Nip and tuck

The 1986 season was a classic case of the team with two strong contenders ultimately losing out because both men won races and took points off each other, while their main rival scored consistently well. Indeed, in 2007 McLaren was to be on the losing end of an uncannily similar situation when Ferrari’s Kimi Raikkonen usurped Fernando Alonso and Lewis Hamilton.

In 1984, the TAG/Porsche-powered McLaren had dominated the World Championship, and Niki Lauda beat Prost to the title by the tiny margin of half a point.

The following year the Frenchman finally won in his own right, although as turbo engines began to reach record power levels there was increasingly strong opposition from Ferrari, Lotus-Renault and – and especially at the end of the season – the potent Williams-Honda combination. Despite its sophisticated electronics package, the TAG engine was beginning to lose out.

McLaren thus knew that ’86 would be a serious fight. Nevertheless, the team went into the new season with a C-spec version of John Barnard’s MP4/2 – which had already served the team well for two years – rather than a totally new car.

However, that decision was also an indication of how good the original concept really was, and there were some updates. A restricted 195-litre fuel tank size for 1986 made packaging easier, and that allowed the driver to sit lower in the cockpit, in a less upright position. The roll-hoop above the drivers’ knees was in fact 12cms lower.

Driver comfort was also improved by the relocation of the gear lever inside the tub – previously it came over the top of the right hand side of the chassis. That move was also a result of the relocation of the turbo inlets for improved aero efficiency around the “Coke bottle” shape at the rear.

The TAG engine was barely changed from the previous year. However, the car featured a revised gearbox, with a sixth gear now added to take advantage of the ever-increasing power levels. It also had a revised oil system.

The Flying Finn

The other big change was the arrival of Keke Rosberg as Prost’s new team-mate and replacement for the now-retired Lauda. Rosberg had briefly driven for Ron Dennis in F2, and one of his reasons for switching from Williams was a little unusual.

“I knew that my time was coming to an end"

“I knew that my time was coming to an end, and before I left I wanted to see how Ron operated,” he recalls. “I was very marketing oriented, it interested me a lot, and Ron certainly had the best marketing department in F1. I definitely wanted to see how he operated, and it was a very useful season in that way, so I got what I wanted.”

The Finn soon made it clear that the TAG engine was lacking in top-end power compared with the Honda he was familiar with at Williams. He also got off to a bad start with a testing crash in Brazil, which did not impress Barnard, who had long-established a great rapport with Prost.

More importantly Rosberg’s driving style was very different from that of Lauda and Prost. He would struggle throughout the year to repeat the form that he’d shown at Williams, and the team had to adjust the car to suit him, although that process didn’t happen until several races into the season. The set-ups used by the drivers were very different, and that of course caused problems when it came to the spare car.

“The car just plainly understeered too much for me,” says Rosberg. “We had one terrific test in Brands Hatch where I was brilliantly quick only because John Barnard was engineering my car, and he got the understeer out.”

The season got off to a disappointing start in Brazil, where both cars retired with engine problems – although at least Prost led. Alain then finished third in Jerez before scoring a well-judged win at Imola, a race that was all about managing fuel consumption. Then in Monaco he scored another superb victory, leading home Rosberg in a triumphant McLaren one-two.

He could have won at Spa, too, but after a first lap tangle he could only manage to recover to sixth in a car that had a broken engine mounting, and was not handling well.

While other cars were plainly faster, Prost kept scoring. He finished second in Canada, third in Detroit, second in France, logging points all the while.

Fuel if you think it’s over

At Brands Hatch he was again third, but conserving fuel, he finished a lap behind the dominant Williams pair. At that stage even the Frenchman thought that a successful title defence was unlikely. Then in Hockenheim the electronics played tricks on him and he ran out of fuel, pushing the car across the line in sixth place to demonstrate his frustration with rules that placed an emphasis on consumption. Rosberg endured similar frustrations.

“Our fuel gauges were so inaccurate,” Keke recalls. “It wasn’t a McLaren problem, there just wasn’t the technology in those days to compensate for temperature, volume and all those factors. We put chilled fuel in, and it came out boiling, and the volume changes dramatically in the mean time. We just weren’t able to measure it.

“I was really fed up with falling out of races, leading and running out of fuel. And Prost too, but Alain managed his fuel better than I did. I went too close, trusting the gauge. I didn’t go over, but I trusted the gauge. Again and again – I ran out of fuel leading in Hockenheim, I ran out of fuel at Imola, I don’t know how many places.”

Prost subsequently won in Austria. In Italy he was black-flagged after switching to the spare car just before the start. He then took priceless second places in Portugal and Mexico. In the latter race he struggled home on five cylinders, worried that the engine might not make it out of a pit stop. He also had to nurse a worn-out set of tyres.

Leaving it to the last gasp

With just the finale in Australia to come, Prost and McLaren had won only three races. But the Frenchman’s relentless scoring had kept him in the title hunt with the Williams drivers. Going into Adelaide, Mansell led on 70 points, while Prost had 64 and Piquet 63. This was still the era of the 9-6-4-3-2-1 scoring system, so Alain had to win the race to stand any chance, regardless of what happened to his rivals.

"We had nothing to lose, and it was a combination of strategy and working very hard with the tyres"

Since he needed a win to steal the title, most people discounted Prost, especially after the Williams duo hogged the front row in qualifying, with Ayrton Senna’s Lotus third. But Prost did his sums, and he knew that over the race distance, McLaren had a strong package.

“We had nothing to lose, and it was a combination of strategy and working very hard with the tyres,” he said. “We knew that we had a problem with the tyres, and we had a strategy also with Keke. And the ambience within the team was also very good, although we knew it would be difficult. We put all the chances on our side, let’s put it this way. Then when you achieve the result it is very, very good.”

Meanwhile Adelaide was also the final F1 start for Rosberg, who had endured a disappointing season during which little seemed to go in his favour.

“I wouldn’t say it was frustrating,” he says. “You’re fighting to get the best out of the car and to improve it, because there’s no way you’re going to admit that you can’t improve it. Of course you can, you always can, but to what extent, remains to be seen. It wasn’t so bad. I finished second in Monaco behind Alain, I would have won Adelaide, I probably would have won Hockenheim, as I was leading and Piquet was running second when I ran out of fuel on the last lap in the forest.”

On the Saturday night Prost relaxed by playing cards in his hotel suite with French journalist friends.

“Ron Dennis strolled in,” he would recall in his autobiography. “‘Too many Frenchmen in here for my liking,’ he said, and beat a hasty retreat.”

He was safely in bed by 11pm, but later a hotel fire alarm ruined any chance of a good night’s sleep, and forced the entire F1 circus down into the lobby!

The race of champions

Mansell led away from the start, but, knowing that this was going to a long haul of a race – and with the title in the offing – he was pacing himself, and Piquet, Senna and Rosberg all nipped past before the end of the first lap.

Rosberg was really flying in his last Grand Prix start, and he passed Senna on the second lap and then Piquet five laps later to claim the lead. Prost meanwhile was also on the move, passing Mansell for third and then Piquet for second, before the Brazilian spun and dropped back down to fourth.

Thus by lap 21 McLaren had a one-two, with Rosberg ahead of Prost. Mansell was still running strongly in third, so the title would still be his even if Keke waved Alain through.

Before that swap could happen while running closely behind his team-mate, Prost hit a kerb and picked up a puncture. It led to a long stop of 17 seconds – even for those days, it was a big loss. The upside was that he now had fresh rubber for the last two-thirds of the race, and that was to prove crucial, although nobody knew at the time.

Tyre troubles on the horizon

This was only the second Adelaide race, and thus Goodyear was keen to check on wear-rates at a track where everyone was planning to run non-stop. Prost’s discarded tyres seemed to be in good shape, so the message went round that a single set would get to the end as intended.

Rosberg continued to lead strongly – until a rear tyre delaminated. Because it remained inflated the Finn thought the rubber flapping against the rear bodywork that he heard was due to a crankshaft failure, so he switched off and stopped. It was only when he climbed out that a marshal pointed out the tyre, and Keke realised that the noise had been caused by the flailing rubber.

Meanwhile, Keke’s departure left Mansell in the lead, and seemingly destined to pick up his first World Championship.

However, the brutish turbo cars put a lot of load through their rear tyres, and if one could fail on a McLaren, there was every chance that it would suffer on the more powerful Williams. Should the team bring Mansell in for a precautionary change? The deliberations in the Williams team’s pit were ended when Nigel’s left-rear gave way spectacularly on the straight.

The car slid from left to right, but somehow the Englishman kept it going in the right direction before coming to a stop at the end of an escape road, his title hopes now seemingly done unless his rivals also retired. The decimated left-rear gave one last forlorn spin as Mansell flicked off the ignition and jumped out unharmed.

Fortune now seemed to smile on Piquet, who was destined for the title if he won. However, safety concerns were now paramount, and in consultation with Goodyear Williams decided not to take the risk of a repeat failure. After leading for two laps Nelson was called in for fresh rubber. And who did that put into the lead with 18 laps to run? Alain Prost…

Having already changed tyres following his puncture, and driven with his customary smooth style, Alain was now in great shape. However, on significantly fresher rubber, Piquet was pushing hard to catch him, and then in the closing laps those familiar fuel consumption concerns became a source of stress for the McLaren driver.

Fuel for thought

“For the last 15 laps my fuel readout showed that I was five litres short,” Prost explained after the race. “So I never reckoned there was any chance of making it. In other circumstances I would have eased right back and tried to conserve things, but on this occasion I had to win, so I forced myself to believe the computer. I just pressed on and, as it turned out, I finished with it still reading five litres down. There was something wrong with the computer…”

Prost kept going, ignoring the pessimistic fuel readout, and he eventually crossed the line 4.2s clear of Piquet. He was World Champion for a second time – and in so doing he became the first man to successfully defend the title since Jack Brabham way back in 1959-’60.

He immediately stopped the car on the track and climbed out, and showed his surprise and delight with a jump that was to become an iconic image – not just of that day, but the whole ’80s era.

“Alain parked the car after the finish-line and then there was this picture of him jumping in the air,” Dennis remembers. “He was a foot or so in the air. It was an amazing picture and it still holds very clearly in the memory.”

That evening Ron, Alain and the rest of the McLaren team celebrated in some style.

“Perhaps the best feeling of all came the following morning,” said Prost. “I was going down to breakfast and the morning newspapers had been left outside the bedroom doors. The headline said ‘Prost wins Adelaide Thriller.” And there was the photo of me, jumping for joy beside the car. I’ll never forget that moment. Absolutely fantastic.”

Rosberg joined in the Sunday night celebrations, which also marked his retirement. His exit from the race was bittersweet, but later he learned something that made him appreciate that he had perhaps been fortunate.

“My best race at McLaren was my last race. In Adelaide I was leading by nearly half a minute when the tyre fell apart, the same thing that happened with Nigel at Williams. In those days it was different, you just took a deep breath – I survived. And that was the end of it.

“When I went to pick up my stuff from the factory I learned from my engineer Steve Nichols that my brake discs wouldn’t have lasted another lap. Again, somebody was looking after me, and it was very good that the car retired. When you hear that, you think it’s not so bad for the very last race...”