Since 2013, the event on Belle Isle, an island in the Detroit River, has been a double-header, with one race on Saturday, one on Sunday. After two practice sessions on Friday, a qualifying session would be held on Saturday morning and Sunday morning for the following race.
However, the packed nature of the schedule meant that IndyCar needed to save time by running two groups of 12 or 13 (depending on entry list size). Whoever had the fastest time across the two groups would earn pole and his group would occupy the odd-numbered side of the grid – P3, P5, P7, etc. while the fastest driver of the other group would line up on the outside of the front row, and his group would start from the opposite side of the grid.
In Sunday’s qualifying session, the group that ran second on Saturday would hit the track first, and therefore have the less favorable track conditions (less rubber down on the track surface), and the previous day’s qualifying process would be repeated.
However, this final IndyCar event on Belle Isle – the Detroit GP switches to a downtown venue in 2023 – is a single race. So despite being supported by the IMSA WeatherTech SportsCar Championship (as usual), Indy Lights and the Masters Endurance Legends, there is enough room in the schedule to run IndyCar’s regular style of qualifying.
That comprises of Q1 which features two groups of 13, the top six from each then graduating to the 12-car Q2, and the top six in that portion advancing to Q3, the Firestone Fast Six shootout.
This means that when drivers are shooting for pole, there are only six cars on track, theoretically making it less likely that a driver will trip over a rival on a warm-up lap, and halving the chance of a shunt that could cause a red flag and produce an unworthy pole-winner.
The ‘Detroit-style’ two-group qualifying system briefly expanded in the COVID-afflicted 2020 season (although ironically, Detroit was among the events canceled) because Road America, Mid-Ohio and the Harvest Grand Prix on the Indianapolis road course became double-headers in compressed race weekends.
