Sebring International Raceway has begun to take its toll on the IMSA WeatherTech SportsCar Championship GT Le Mans class competitors, as this year’s Mobil 1 Twelve Hours of Sebring is past the halfway point.

There have been a variety of leaders thus far. Each of the five Michelin technical partner teams from Corvette, Ford, BMW, Porsche and Risi Ferrari have had their turn in the lead at various points, and no one manufacturer has held a significant advantage.

At the six-hour mark, polesitter Connor De Phillippi led in his No. 25 BMW Team RLL BMW M8 GTE from Toni Vilander in his No. 62 Risi Competizione Ferrari 488 GTE under the fifth full course caution of the race.

The number of yellows, five, is one more in six hours of racing at Sebring than occurred in 24 hours of racing at Daytona to kick off the season.

Three of the nine cars in class have had issues within the first six hours.

For the No. 3 Corvette C7.R, which won last year in the hands of Antonio Garcia, Jan Magnussen and Mike Rockenfeller, its chances at a repeat victory evaporated early.

The car sustained a left rear puncture from contact on the opening lap, which forced the car in for an unscheduled stop.

#Michelin engineers confirm a puncture due to contact on the No. 3 @CorvetteRacing at start of race, T1. Car returned to pits for left rear tire change. #Sebring12 #IMSA pic.twitter.com/WMfb1A8z9E

— Michelin Racing USA (@MichelinRaceUSA) March 17, 2018

Things went from bad to worse with a series of mechanical issues later in the race, including a battery change that cost the team multiple laps, and a further power steering issue.

Meanwhile, contact between the No. 24 BMW Team RLL BMW M8 GTE and No. 66 Ford Chip Ganassi Racing Ford GT took both of those cars out of the fight as well. The BMW lost eight laps with a water leak while the Ford went behind the wall to repair rear end damage. Ford confirmed contact between the two cars, which caused a cut tire.

The No 24 BMW M8 of @nickcatsburg @Jessekrohn @JEdwardsRacing is unfortunately down 8 laps after repairing a water leak from contact with the No 66 Ford. @IMSA #Sebring12. 7 hours to go.

— BMWUSA Motorsport (@BMWUSARacing) March 17, 2018

From a bit earlier, #Michelin engineers have inspected the damaged LR tire from the No. 66 Ford GT, which suggests a possible curb scuff or contact. The team confirms there was contact. #Sebring12 #IMSA pic.twitter.com/zpkuExvnQC

— Michelin Racing USA (@MichelinRaceUSA) March 17, 2018

#FordIMSA | No 66 behind wall for extra work on damage caused during that last restart #Sebring12 pic.twitter.com/Qc5oZIWn9m

— Ford Performance (@FordPerformance) March 17, 2018

The No. 24 BMW had delivered excellent early race pace in cooler conditions before the temperatures increased. Jesse Krohn’s early race fastest lap of 1:57.622 beat last year’s fastest race lap set by Patrick Pilet (No. 911 Porsche, 1:57.764) within the opening hour of the race.

Overall and in Prototype, Pipo Derani led in the No. 22 Patron ESM Nissan while Luca Stolz leads in GT Daytona in the No. 33 Riley Mercedes-AMG GT3.