Indycar drivers can choose between grooved rain tires or two kinds of fast, sticky slicks during a race.
With new concrete poured on the Belle Isle track combining with consistent rain throughout the weekend, drivers said it often became like trying to race on ice.
Race One on Saturday was actually called with roughly a half-hour scheduled to go because of a threat of lightning in the area.
By then drivers Carlos Munoz and Marco Andretti had switched to slicks and gained significant ground on the rest of the field as the track began to dry, eventually finishing first and second, respectively.
Drivers went to slick tires quickly in Race Two, but many began sliding on the still-wet track and the last 15 laps were littered by a series of accidents and restarts.
Driver Sebastian Bourdais kept the lead for the win despite nearly running out of fuel.
Team Penske had a tough time on its home track.
Driver Will Power recovered from an electrical problem only to crash into teammate Helio Castroneves near the finish of Race Two, knocking both cars out of the event.
In fact the best-known driver in Indycar racing has been mostly forgotten the past two weeks.
Castroneves suffered a frightening back-flip crash practicing for the famed Indy 500 on Memorial Day weekend.
Then he lagged behind the leaders during both Indycar races this weekend at the Detroit Grand Prix on Belle Isle, before being taken out of Race Two by his teammate.
But Castroneves tells WDET’s Quinn Klinefelter his love for Belle Isle, where he won his first-ever Indycar race, remains strong, even as he remains puzzled about what caused his car to flip upside down at Indy.