I used this one first. Now I simply do 1/2 and 1/2 distilled white rice vinegar and water. I used to add scents in the beginning because it is a tough smell, but on the other hand it goes away quickly, so I don't bother anymore.
As long as you have a good car soap/shampoo and it should be slick enough to not scratch the car if you keep the microfiber washed out frequently. (Don't go over a spot that has dirt on it and then continue over the whole hood or something before washing the microfiber out, etc).
But if you want to turn it up to 11, get an electric power washer that's about ~1.2 gal a min. Should be high enough pressure that you get good cleaning (and fantastic foaming if you get a foam canon for it and car shampoo) but low power enough that you won't damage your paint. THEN get a DI system, it's expensive up front, and probably will run about $100 every year or every other year, but you don't have to touch your car AT ALL when drying it. Just let it air dry and it'll be spotless. Power wash off heavy stuff like dirt and mud and bugs, foam canon soap and very gently go over it in linear movements with a microfiber, and DI power wash rinse it and walk away.
I've used it at least 5 to 6 times so far for probably 15 to 20 minutes each time at 1.2 gallons a minute and the water is still reading 0 total dissolved solids. DI water systems are used in research labs when you need absolutely pure water and my car will dry with zero spots now, it's fantastic and I don't have to worry about scratching it (swirl marks) when drying (which is when you don't have any lubricating products on it from the soap).
Edit: Also, I may be kind of a crazy person when it comes to this.... I actually work in a research lab and my coworkers thought I was joking when I said I bought a DI system to clean my car.... lol