'A game of two halves' is a cliché belonging to a very different sport, but yet it manages, almost perfectly, to summarise the 2012 Total Spa 24 Hours.

The first half was blighted by safety car periods at the rate of one an hour, the second relatively uninterrupted.

The first half was and soaked by torrential downpours that reduced the track to little more than a skating rink the second entirely dry, lap times coming down accordingly.

The first half belonged to BMW and Marc VDS Racing, the second was all Audi as Frank Stippler, Rene Rast and Andrea Piccini secured a second consecutive win for the four ringed brand in a year that has already included endurance wins at Nurburgring, Bathurst and, of course, Le Mans.

The trio, sharing the #16 R8 LMS ultra for Audi Sport Performance Cars Team Phoenix increasingly took a stranglehold on the race lead in the second half of the race, winning the internecine battle with their Audi colleagues in the #1 car.

Both teams – Christophers Mies and Hasse sharing the #1 with Stephane Ortelli – ran near faultless races, a few punctures for each car the only problems encountered in the entire race. The battle between the two team was close right into the closing hours when during pitstops under a sixteenth and final safety car period of the race Ortelli was held by a red light at the end of the pitlane, a delay then bulked up to a complete lap when the Monagasque driver was handed a deserved drive through penalty for a late entry into the pitlane.

While faultless, however, the two Audis – and the Ingolstadt brand in general – had not had a simple race, with the early lead belonging almost exclusively to Marc VDS Racing and BMW.

After a torrential, if short lived, downpour had cancelled the planned Super Pole session Z4s occupied the front row, Frank Kechele and Maxime Martin leading the field of more than 60 cars down into Eau Rouge past the endurance pits to start the race. There the race started with a bang – though thankfully not literally – as Martin and Kechele battled wheel to wheel through the Spa track's signature corner, Martin emerging over the crest at Radillion in the lead.

Having topped qualifying both BMWs eased away into an early lead over the chasing group in the early hours, the best of the rest slot early one filled not by Pro Cup Audis, but by the Pro-Am entries of McLaren – with Alvaro Parente and Von Ryan Racing – and Porsche with Uwe Alzen driving the opening stint in the Haribo Racing Team car. The experienced German was  a star of the opening hours in a fantastic battle with Audi drivers Edward Sandstrom and Stippler, DB Motorsport's Stephane Lemeret and Eric van de Poele in the Boutsen-Ginion Racing #5 McLaren, another Pro-Am contender for Pro-Am honours right up to the point it was savaged out the race at La Source by a lapped car during the hours of darkness.

BMW's short time of dominance was brought to an end by the first safety of the race as La Source was transformed into an obstacle course of standing water and stranded cars as the Ardennes weather played its trump card.

Finding no grip under braking cars spun left, right and centre, Julien Draper taking the centre route, aquaplaning gracefully into the tyres in the Von Ryan McLaren, the sister car to Parente's charge, crabbing back to the pits for a costly visit to the garage. The safety car was scrambled to prevent any further damage in the terrible conditions, but not before Andrew Danyliw has crashed his BMW against the pitwall, bringing about one of the race's first official retirements.

Not only did the safety car delete the early lead held by Bas Leinders and Maxime Martin for Marc VDS Racing but the dramatic change in conditions forced the Vita4One Racing Team #66 started by Kechele into making two pitstops, dropping them out of the lead battle with a deficit they would spend the remainder of the race trying to make up.

Now without the Z4 rear gunner Martin and Leinders raced on as a two handed effort, keeping Markus Palttala out of the car to avoid having to a penalty as the Blancpain Endurance Championship leaders sought  the maximum points awarded at both the six and twelve hour marks.

Martin – just – managed to lead after 6 hours. The one quarter marker coming only seconds after the end of the third safety car of the race – the second of the race for torrential rain. Having lost the lead when he pitted under the safety car Martin passed both Haase and Piccini, cautious in the conditions, in the final sector of the crucial lap to be the first car across the line at six hours to collect 12 points.

Despite only running with two drivers – Palttala had a penalty hanging over him from qualifying when he improved his best time under yellow flags – Marc VDS remained an almost constant force in the first half of the race. They held the lead for most of the first 12 hours, despite scares with contact with both the Gulf Racing McLaren and Filip Salaquarda's Vita4One team Italy Ferrari, the latter incident ending Salaquarda's race after he lost control under braking and speared into the wall, pushing the Marc VDS car into a harmless spin.

The half way mark, however, marked a turning point. An ill-timed pitstop during another safety car period found the Marc VDS car trapped in pitlane by the red light, plummeting to fifth place. The delay was compounded when the team put Palttala in the car for the first time of the race, the waiting penalty delaying them further.

From that point on it was all Audi, Marc VDS unable to make up ground owing partly to a clutch issue that delayed them in each of the almost hourly pitstops, maximum stint time governed closely by the Blacnpain Series rules.

The #16 and #1 crews fought for victory until the closing hour when the final safety car – the second half of the race including only four -relatively short – interventions – split the two cars.

They completed the race split by a full lap of the 7km track, with the Vita4One Racing car of Kechele, Greg Franchi and Mathias Lauda in third at the end of a long fight back after their early loss of time. Their spot on the podium came despite Kechele limping across the finish line with a right-rear puncture on the BMW shredding the bodywork in the final lap.

The Vita4One squad was not the only team to have to fight back from early problems. Audi had combined Le Mans winners Marcel Fassler and Andre Lotterer with endurance legend Tom Kristensen to staff the #6 car, the trio rightfully attracting much pre-race attention. However, their challenge for the lead ended early, starting driver Lotterer the victim when Adam Christodouou arrowed his McLaren into the pitlane too late. The contact pitched the McLaren into the barriers, and would leave Christodoulou excluded from the race, but Lotterer too would have to return to the garage, losing half an hour to suspension repairs.

Coming back from as low as 63rd overall after two hours a faultless drive – a testament to what could have been – lifted the car into sixth overall at the checkered flag, crossing the line at the end of the race with their two Audi teammates. The fourth works supported Audi – the #2 Audi Sport Team WRT entry had been a contender for podium places until just four hours to go when Edward Sandstrom joined the illustrious list of drivers to crash through Eau Rouge, spinning into the tyres after running too far up the kerbs at the fearsome uphill corner.

In sixth Fassler, Lotterer and Kristensen trailed the Marc VDS entry (fourth) and the winner of the Pro-Am cup in fifth place overall.

For AF Corse Niek Hommerson, Louis Machiels, Andrea Bertolini and Pier Guidi Alessandro won the class the sole survivor of three Ferrari's run by the Italian team that dominated the class in the second half of the race.

The whittling down of the AF Corse charge – through mechanical problems – echoed the problems encountered by much of the class.

After a blistering early run by starting driver Bernd Schneider the British Preci-Spark team were ruled out of contention by  a persistent misfire. Boutsen-Ginion Racing #5 was taken out by Lapidus Racing's McLaren in an ill-advised overtaking attempt under the cover of darkness. The Peter Kox led Blancpain-Reiter entry ran well, but a series of late race excursions, including a trip across the grass that damaged the splitter, kept them just outside the top ten overall.

Instead it was steady – if unspectacular runs that were rewarded – with the Haribo Racing Team Porsche and #10 Ferrari of defending class champions SOFREV ASP taking podium finishes and top ten results overall.

First Motorsport took a comfortable win with the Gentlemen Trophy over the Bull Fight Racing Dodge Viper with SpeedLover – the only car to finish the all-Porsche Cup class 25th overall, completing 455 laps.

Despite missing out on the overall podium Martin, Leinders and Palttala continue to lead in the points standings, though second placed Mies, Haase and Ortelli now trail by just 15 points with two rounds – Nurburgring and Navarra – remaining. In the Pro-Am ranks the class win a Spa lifted Hommerson, Machiels and Bertolini to the top of the points, though Bertolini trails his teammates by a solitary point gained at Silverstone.