The ultimate test of endurance

It's the fourth season of the Challenge, which first ran in 2016 with three races and has now expanded to include five of the world's biggest GT events for a total of 63 hours of competition. This year manufacturers and drivers will be competing to get the best collective results across races in Australia, the US, Belgium, Japan and South Africa. All on Pirelli tyres.

Feel the heat
The championship gets underway at the legendary Bathurst 12 Hour in Australia from 1-3 February, as a selection of the world's most accomplished GT drivers are joined by the country's best domestic drivers for a race from the cold darkness of dawn into bright daylight.

It might be known as a test of endurance but, make no mistake, this is always a sprint. Victory-clinching, career-defining overtakes have taken place in the dying seconds, making it an unpredictable show right to the very end. 

It's all about finding the best grip, but that's hard when conditions change constantly. As night turns to day there can be up to 15 degrees of temperature change, drastically affecting handling as the race wears on.

The exotic line-up of GT3 machinery combined with a half flat-out, half twisty mountain layout means that anyone brave enough to risk brushing the walls lining the back of the circuit can make massive gains; almost like racing in Macau.

At Bathurst, thundering Bentleys and Nissans fly down the Conrod and Mountain Straights, while the agile McLarens and Audis thread the needle with clinical precision up the hill towards Skyline, immediately dropping like a roller-coaster off the edge of a cliff at The Esses and The Dipper. The names of the corners alone tell the story of this incredible circuit.

Getting it right in California 
Drivers will experience a similar feeling from 28-30 March, as the same thundering GT3 machines barrel through Laguna Seca's iconic Corkscrew for the California 8 Hours: round two of the Challenge. It's an adrenalin-filled downhill kink that forms the most recognised part of the American track. 

On this astonishing circuit, there's so much that can catch a driver out. A common mistake is tripping over a rival in the braking area on the way down to the tight, double-apex left-handed Andretti hairpin, which comes straight after a long burst of throttle on the start-finish straight. In particular, it's important to look out for the variable grip at different points on the track, which can be affected by sand blown onto it. The carefully-planned tyre strategy will be compromised if there's a flat-spot on the tyres; which can happen after just one distracted moment of late braking. Endurance racing is all about getting it right, consistently.

Round the clock
Next comes the toughest endurance test of them all: the 24 Hours of Spa in July.

Everyone involved is pushed to the limits – whether it's the strategists perched on the pit wall monitoring the ever-changing complexion of the race, or the Pirelli technicians working round the clock to ensure teams have the right rubber available to find that extra tenth of a second to make the difference. Then there are the GT3 drivers themselves – trying not to tangle with lapped traffic in the dead of night, two-and-a-half hours into a gruelling stint in which they've already had to nail the scary Eau Rouge/Raidillon uphill left-right-left combination 60 or more times. Many will start the race on the Saturday afternoon, but only some will reach the other side of midnight and cross the finish line on the Sunday. Without a doubt, it's the jewel in the crown of the championship.

See the bigger picture 
The Challenge moves on to its fourth continent out of five for the Suzuka 10 Hours in Japan in August, where head must rule heart. Drivers adore Suzuka's first sector, a ribbon of fast, flowing left and right corners that seamlessly blend into one another. Lean on the tyres with all the prodigious downforce that modern GT3s offer and you'll experience pure driving pleasure. But there are 10 hours to go – and several team-mates in the car who will want fresh tyres for later – so it's important not to go overboard and burn through them. Part of the art of endurance racing is always to see the bigger picture.

Drivers need plenty of grip left over in any case for the punishingly long double-apex Spoon Curve, as well as to avoid potential disaster at 130R. Get that even slightly wrong and there's a risk of fluffing the lap-ending chicane, a prime passing spot. If you're lucky. If you're unlucky, it's a colossal accident. Repeat correctly up to 280 times and you'll be fine.

New territory
The grand finale of the championship in November is both something old and something new. It's the first time the Kyalami 9 Hour has been on the calendar for the Intercontinental GT Challenge Powered by Pirelli, but its list of former winners in other incarnations is impressive. The Belgian racing driver Jacky Ickx notched up four victories on the circuit, while the Scuderia Ferrari team has three wins and Joest Racing four. Other winners include Stefan Bellof and Derek Bell in a factory Porsche 956. All legends who underline the race's heritage. 

Kyalami was reconfigured only a few years ago, so drivers meet on something approaching a level playing field. But there are plenty of traces of the old circuit in place, including Sunset Corner, its name derived from the setting sun that glares right into the drivers' eyes as they fling their cars through a fast right before stamping on the brakes to slow down for the next left-hander.

A title decider where no one knows the favourite will provide an enthralling finish to 63 hours of on-track battles, hundreds of pit-stops for fuel and fresh rubber and the crazy schedules of endurance racing. And finally a chance to catch up on the nights of lost sleep for the teams and their crews.