I FIGURED IT OUT!

when Jack and Reggie are leaving the police station for the first time after Jack gets Eddie out for 48 hours, there's a wide-angle shot of them in Jack's Cadillac going down the road, and it looks like Luther is two cars ahead in Reggie's Dusty small green Porsche. In fact, it is Luther in Reggie's car shown on screen before they even get to the parking garage where Luther first picks up the car.
I figured this out because directly after Luther picks up the car from the parking garage later on in the film and Reggie and Jack are following him it's the same piece of footage used for the scene when they first leave the police station before Luther even gets the car. The editing staff for the movie just use the same piece of footage for when they first leave the police station and when they first start to follow Luther in the car.
HAH!