I give it 4 stars because if you dilute it as it says, it does not produce as much foam.
For better results, put more material than recommended in the foamer.

I got the one-liter package for testing. I tried it with the Nilfisk 135 bar pressure washer and the Nilfisk extra foam sprayer.

I put 70-80 ml in the bottle and it indeed produced the thickest foam I have seen so far. It stays on the car for a longer time and works more effectively. However, it leaves a dust film that we remove with a leather cloth. I will also get the larger package!

I deduct one star because while the seller mentions "impressive shine," what I noticed is that it probably removes the shine-wax from previous shampoos! It is effective, "sticks" to the car, and only comes off with the pressure washer!

Related video: https://youtu.be/5K9xf-gtIa8

Excellent product. Without having a foam dispenser and hand washing with a sponge, incredible result. Even the toughest stains are removed with just one swipe. Bravo to the company for the very good product. It was my mistake not to buy the larger 5-liter packaging. It delivers what it promises.