As Formula One hit the road today in Australia, it did so with a raft of rule changes and technical enhancements designed to improve the racing. That changes are mooted almost every season, largely focusing on encouraging more overtaking, will not have gone unnoticed, even to casual observers. Yet, in America last weekend, a worldwide series held its opening meeting, featuring cars comparable in performance to those of F1 going wheel to wheel. Fifty-six of them. For 12 hours solid. There was no shortage of racing, no shortage of overtaking and at the chequered flag the first three cars were separated by only 45 seconds. It is motor sport's best kept secret.

Britain's Allan McNish drove in F1 for Toyota in 2002, but since 2006 he has been an Audi Sport factory team driver as part of its sports car programme in endurance racing – a form of the sport that most will be familiar with from the Le Mans 24 Hour race (which he has won twice) that this year forms the centrepiece of the first full season of the Intercontinental Le Mans Cup (ILMC), an endurance racing series set up by the Le Mans organisers, the Automobile Club de l'Ouest.

McNish, who was driving in the series opener, the 12 Hours of Sebring, in Florida last weekend, admits that endurance racing was, at first, a surprise even to him: "Until I came to see it myself by racing in it, I didn't appreciate it in totality, then I thought, why did I not look at this before?"

The cars are sub-divided into classes by performance, a factor in the appeal. With the fastest cars 30 seconds a lap quicker than the slowest, it is dealing with this "traffic" that demands attention. Done with skill, it can be a race-deciding factor: "You've got a lot of constant excitement, it doesn't dull down, it actually is a race from the start to the end, flat out with that constant focus. That's why the drivers like it. Because they have to combine this intensity with a really fast car," says McNish.

It is also, he argues, easily comparable with F1. "If you're talking about the cars and the technology, it's equal to F1. In terms of performance, downforce levels, power, and torque, things like that, it's Formula One standard. And that's why I think now, there are a lot of drivers who have had good strong careers in F1 adapting very well to this style of racing." Only the added 300 kilos of weight make a difference. And that means "you've got to throw the car around," says McNish.

Anthony Davidson, driving for Peugeot, another of these ex-F1 drivers who is enthusiastically embracing endurance racing, agrees: "It's the closest thing to an F1 car I've ever driven. As soon as you wind them up, they're great at high speed."

"After leaving the world of F1 and joining the sportscar scene, I suddenly realised it was like this secret of motorsport that no one has discovered. The cars are fantastic and the scene is brilliant," he said. McNish also vouches for Davidson's enthusiasm: "Anthony and [Giancarlo] Fisichella have come from the same sort of arenas – single seaters and you see a smile on their faces because we love to race, we're racing drivers, we're passionate about our racing."

That the greatest sports car race in the world, the Le Mans 24, has not formed part of a series since the World Sports Car Championship folded in 1992 and is now at the heart of the ILMC is no coincidence. It is central to the direction the manufacturers, teams and drivers want it to go. Becoming a fully-fledged World Championship is surely the purpose of this nascent series. Indeed, the FIA president, Jean Todt, who was boss at Peugeot in the championship's last incarnation, has said "endurance racing could be an area we are interested in" regarding World Championship status. It is a realistic possibility, especially given the paucity of quality of opposition on offer in motor sport Championships at the moment, and, if it were granted, would make it the second most prestigious in the sport, below only F1. A goal not to be sniffed at.

In the 1970s, the World Championship was as popular, in terms of crowds and coverage as Formula One. It was only the slow departure of manufacturers that caused the decline, a trend that is reversing rapidly. Where teams like BMW and Toyota had their fingers burned and withdrew from F1, huge investments offering little in terms of results, they are now returning to endurance racing. BMW in the form of a works team that has already won the American Le Mans series and Toyota providing the engine for the Anglo-Swiss Rebellion team – the source of a much-rumoured full-time return. They are not alone. Britain's Aston Martin will be bringing a brand new prototype to compete with Audi and Peugeot at the next race at Spa, Nissan is providing engines for the Signature team and they are in the classes below joined by cars representing Ferrari, Lotus, Chevrolet and Porsche.

The reasoning behind this renewed interest goes beyond just offering exciting racing for the fans and suggests that more manufacturers will follow. Audi Sport's team boss Dr Wolfgang Ullrich sees it as two-fold at least. "We always try to have technology in our race cars first, before they then go into our road cars and are made available to out customers," he explained, pointing out that the direct fuel injection and diesel technology that has seen his team win Le Mans nine times in the past 11 years both transferred directly into road cars. "That's missing in Formula One, There is no connection at all. What you learn in F1 you can't use for your customer. As long as the tehnology in Formula One is not relevant for our customers it makes no sense to go there," he emphasised.

There are also potential longer term gains in terms of marque prestige. A lesson Dr Ullrich also recognises and that for many has been long since forgotten: "Many big names in racing, like Ferrari – the brand – have this great name not because they've been successful in F1; they have it because they have been very successful many, many years ago in endurance racing – that's where it comes from."

Success eluded McNish at Sebring. After having his car damaged by an ill-calculated overtaking manoeuvre by Marc Gené in the Peugeot he managed a creditable fourth having been laps down in his R15 – the car's final race (view the gallery from the race here). He and co-drivers Tom Kristensen (an eight-times Le Mans winner) and Dindo Capello (three times) will be using their brand new R18 coupe at the remaining ILMC races, a prospect McNish relishes, especially for the British round, the Silverstone 1000km in September.

"All of these cars, iconic cars that you would love to drive on the road, the fastest of today's road generation in race trim, all the sights and sounds, whether it be a Corvette thundering out, a Ferrari screaming or one of our diesels, to watch that through Copse and then blast off down through the Becketts section will be a pretty spectacular sight, then to look back and see all the other cars chasing will make it an intense affair," he said.

But intense and memorable for the fans too: "If they come to Silverstone their eyes will be opened wide. They'll be shocked by every level of it. How advanced from a technical point of view it is, at the hard cut and thrust of the racing, and how accessible it is ... Anybody that goes to Le Mans or to Silverstone would come back for more."

It's an opinion to take seriously. McNish is not going anywhere, the racing's format and intensity is just too good: "We've won and lost races by seconds after driving multiple grand prix distances at just one event. There's no waiting for somebody to drop out or a problem to happen, because of the reliability they don't. You've got to grab a hold of these races and these cars, and drive the wheels off them. It's the only way. The only way for success.

"Its part of the reason I love it – there's no hiding place," he said. Something the sport's best kept secret may find out itself before too long.