Sunday’s wild IMSA race at Road America offered a fairly clear picture of which teams were headed for victory lane after just over 1h40m of the 2h40m race had been completed.

And then the skied opened, which threw expectations aside as a yellow flag, red flag, and green flag influenced a crazed sprint to the checkered flag. Adding to the unpredictable outcome, the finish came under caution as the leaders in GT Le Mans left the tarmac and the final results were shuffled once again.

When it was over, the pole-sitting Acura Team Penske ARX-05 DPi driven by Ricky Taylor and Helio Castroneves were victorious, but only after the DPi lead changed hands moments before the yellow flag for excessive rain with approximately 55 minutes left to run as a hard downpour sent cars from all four WeatherTech SportsCar Championship classes spinning harmlessly or into the walls. Mazda’s Oliver Jarvis nipped by Castroneves moment before the rain hit, and was locked into first place when the yellow and red flags were thrown.

Credit the Penske team for calling Castroneves in for rain tires just as the yellow flag was being unfurled, and most of the DPi teams followed the Acura onto pit lane for the same changeover from dry Michelins to wets. As the red flag lifted, the Mazda’s Jarvis circulated in the lead along with DragonSpeed LMP2 driver Ben Hanley, Porsche GT Le Mans driver Nick Tandy, and Lexus GT Daytona driver Townsend Bell.

A huge strategy error saw Mazda fail to pit Jarvis for rain tires once the pits opened as the field prepared to make a seven-minute dash for victory. Called to the pits as the race went green, Jarvis watched as Wayne Taylor Racing’s Renger van der Zande inherited the lead with Castroneves in hot pursuit entering Turn 1. Running wide at the final corner, van der Zande’s Cadillac surrendered the position to Castroneves, and from there, the three-time Indy 500 winner checked out and scored Acura’s first win of the year.

The victory also turned a year of misfortune around for Castroneves and Taylor, whose best finish across the opening three races was seventh in a class with eight cars.

It was all sunshine and rainbows to Castroneves and Ricky Taylor after their well-executed victory. Michael Levitt/Motorsport Images

“Hats off to all the Acura Team Penske guys,” Taylor said. “Rain or shine today, we were really strong. Helio did an unbelievable job. It’s been a long time coming for us.”

With the finishing order preserved under the caution on the last lap, the WTR Cadillac held onto second, and Action Express Racing’s Pipo Derani — after crashing and destroying the nose when the rain hit — rallied to take third, despite losing time in the pits for bodywork replacement. JDC-Miller Motorsports’ Sebastien Bourdais, coming off three consecutive third-place finishes, missed his first podium of the year after taking fourth.

Antonio Garcia and Jordan Taylor didn’t look likely winners at Road America when Porsche and then BMW took charge, but events played into Corvette’s hands. Jake Galstad/Motorsport Images

If the DPi swing from Acura to Mazda to Cadillac back to Acura wasn’t enough fun at Road America, the GT Le Mans class had its own silliness in store for fans as the pole-sitting Porsche 911 RSR of Laurens Vanthoor lost the lead on Lap 1 to Jordan Taylor, but Vanthoor eventually fought back to recapture the lead before the first round of pit stops. In full control, he turned the car over to teammate Earl Bamber who maintained the lead and appeared to be cruising for the brand’s maiden GTLM win of 2020. Until the showers blanketed the first few corners of the 4.0-mile circuit.

Porsche’s ownership of GTLM met its end as Bamber went for a wild hydroplaning ride entering Turn 1. Bamber’s big advantage in GTLM was traded for a spinning trip through the gravel where his 911 RSR lightly nudged the tire barrier. Although the Porsche was largely undamaged, Bamber was left stuck in the gravel. Losing two laps during the extrication process, the 911 RSR would go from the lead to finishing next-to-last in class.

But all hope was not lost for Porsche as the sister entry was in position to take the lead and keep that first win in sight as the race went from red to green. BMW Team RLL’s John Edwards had something different in mind, however, and motored his BMW M8 GTE to the front of GTLM as Tandy fell to third behind the Corvette of Antonio Garcia.

The presence of Garcia in second was a particular surprise. A brutal pit stop on Lap 40 dropped the car from second to sixth and last in GTLM when a series of wheel gun issues left the C8.R sitting stationary on pit lane as a replacement gun was gathered to tighten the left-front wheel. An apparent issue with the replacement gun added more time to the stop when it was time to change the right-front tire. With the right-rear wheel gun retrieved from the back of the pit stall, the right-front Michelin was secured and Garcia charged out of the box with a need to re-do all of the work he and Taylor had completed.