Car polish is not permanent and typically lasts for a limited time, depending on several factors:

1. Type of Polish: There are different types of polishes—some are more aggressive and designed for correcting paint, while others are more about adding gloss and shine. The longevity can vary based on the formulation.

2. Environmental Conditions: Exposure to harsh weather, UV rays, and contaminants can reduce the lifespan of the polish. Cars frequently parked outside or in areas with heavy pollution may see quicker degradation.

3. Washing and Maintenance: Frequent washing, especially with strong detergents or brushes, can wear away the polish more quickly. Using gentle, pH-balanced car soaps can help extend its life.

4. Application Method: Proper application can influence how long the polish lasts. A well-applied polish with adequate curing time will typically last longer.

5. Layering with Wax or Sealant: If you apply a wax or sealant over the polish, it can provide additional protection and extend the overall longevity of the shine.

In general, car polish may last anywhere from a few weeks to several months, depending on these factors. Regular maintenance and reapplication are usually necessary to keep the car looking its best.