Dear 350Z, for cleaning the marks around foot wells follow these steps:
1. Clean the area with a wet cloth and wipe it dry.
2. then spray colin on the remaining marks, let it be their for around 30 seconds and then wipe it with a soft cotton cloth or Sponge. Sponge is better if the area is too dirty.
3. repeat step 2 if need be.
From my experience, Colin is one of the safest products that can be used for dashboard cleaning.
**Please avoid kerosene, petrol, alcohol etc. Though they clean very well, after prolonged use dull patches will emerge on the plastic surface.