Okay, perhaps I over-generalized somewhat. If one was to exclude the little details and edges, intended to optimize the airflow in the forwards direction, I contend that most cars would be more aerodynamic in reverse due to their general shape.

Here's one data point, merely removing the rear spoiler an SUV has the same drag in reverse as it does going forwards: https://airshaper.com/blog/mercedes-eqc-drag-coefficient

If the same car had the fine details massaged for the reverse direction in a similar way to how they had already been done for going forwards (i.e. instead of the rear spoiler, putting a similar spoiler facing the opposite direction at the front of the car), the Cd would be significantly less in reverse.