Actually, a lot of taxi companies will be switching over to the 300C LW (Long wheelbase) when their Crown Vic's get replaced.
Well, around Detroit it depends what area you're in, but the Detroit PD doesn't have enough money to replace their Econo Vans and Crown Vics. Auburn Hills had had Chargers and Magnums for over a year, if you're near Dearborn you'll only see Ford's, and around Milford you'll most likely see Impala's. Troy is a mix, but I've seen a few undercover Camaro's running highway duty.