At least with the Preakness there is virtually always the hope that you'll be witnessing a horse win the second leg of the Triple Crown. That, combined with it's history, makes it worth going to for racing fans and marketable. The Detroit Grand Prix, much like the Rocket Mortgage Classic golf tournament, is a middle of the road event with no real historic stakes. Hard to market that for anyone, let alone the Grand Prix team who don't seem all that plugged into the City.
At least with the Preakness there is virtually always the hope that you'll be witnessing a horse win the second leg of the Triple Crown. That, combined with it's history, makes it worth going to for racing fans and marketable. The Detroit Grand Prix, much like the Rocket Mortgage Classic golf tournament, is a middle of the road event with no real historic stakes. Hard to market that for anyone, let alone the Grand Prix team who don't seem all that plugged into the City.