I've been using one - not for every wash - for only about a year, but have been serious about detailing my cars for many years. It is not a gimmick. The idea is that some (most?) of the contaminants are loosened and carried away by the foam, rather than being rubbed into your clearcoat with your wash media.

Foam cannons are effective tools for washing a car and are not just a gimmick. Here’s why they are useful:

Benefits of Foam Cannons:

1. Enhanced Dirt Removal:

   Foam cannons produce a thick, clingy foam that covers the entire surface of the car. This foam helps to loosen and lift dirt, grime, and contaminants from the paint, making it easier to remove them without scrubbing hard.

2. Even Coverage:

   The foam creates a uniform layer over the vehicle, ensuring that all areas are treated equally. This helps in reaching tricky spots that might be missed with manual washing alone.

3. Reduced Risk of Scratches:

   By lifting dirt away from the surface, foam cannons minimize the risk of scratching the paint during the hand washing process.

4. Efficient Pre-Soaking:

   Foam cannons pre-soak the vehicle, which softens and loosens dirt before the actual wash, making the hand washing process more effective.

5. Less Water Usage:

   Foam cannons can help use water more efficiently by covering the car with foam and reducing the need for excessive rinsing.

Considerations:

1. Initial Investment:

   Foam cannons require an investment in both the cannon itself and a compatible pressure washer.

2. Proper Use:

   To be effective, foam cannons need to be used with the correct car wash soap and adjusted to the appropriate pressure and foam thickness.

3. Not a Standalone Solution:

   While foam cannons are great for pre-soaking and loosening dirt, they are typically used in conjunction with hand washing to ensure a thorough clean.

Overall, foam cannons are a valuable tool for achieving a more thorough and efficient car wash, especially for enthusiasts and those who want to take extra care in maintaining their vehicle’s appearance.