This is a good product, like almost everything Sonax makes. I have a Mercedes and use Sonax along with P21S Paintwork Cleanser as they are as German as the car. The Sonax Brilliant Shine is a great detailer too. You don`t need a lot of the spray and seal. I used two or three sprays on each panel and it beaded up nicely on the rinse off.
Of course, I have to admit I made a big mistake at first. I watched videos and read the instructions but for some reason I had a mental block after washing my car. I used the spray and seal like you would a drying aid. While the rinse water was still on the car I applied spray and seal and instead of rinsing it off right away I rubbed it into the car while drying it. Huge mistake! There were streaks everywhere and I swore I would never apply this product on my car again. It certainly was not as good as the other Sonax products I have used.
Then the next day it popped into my head that I did this all wrong. I washed the car again and this time was more careful. I applied spray and seal onto the freshly washed paint and rinsed it off, removing it before drying not while drying. That made all the difference in the world and the shine was excellent with no streaks. It has been a month and still doing quite well. Just follow the instructions to the letter and you won`t go wrong with spray and seal. One bottle will last you three applications on a normal size sedan although I suppose the more product you spray the better chance of full coverage.