Originally Posted by canistel
In my opinion, I would try some (watered down) vinegar first; I have a hard time believing it will damage anything. My parents have used that exclusively all their life, both on the cars and in the house, never had any damage issues whatsoever. It's safe, cheap, very effective, and easy on the environment. Most of those other cleaners nowadays are nasty stuff.
There are too many products available to resort to household solutions. Using these can potentially scratch and will remove everything from the surface (I'm referring to paint mainly, as you're likely to splatter vinegar on the paint when cleaning glass and in many cases people like to use vinegar directly on their paint, which is an acid). The main reason for using automotive detailing products is to not only maintain / clean the vehicle, but also add additional properties such as polymer or carnauba based sealants. Vinegar removes everything and can scratch paint since there is no lubricity in it, which would occur from the rag/towel you're using. Plain and simple, it may work, but was never designed to be used on vehicles.
Steel wool will also scratch glass; again it wasn't designed for this. There are several products available that are great to use and will keep the surface of your vehicle in perfect shape.
You're obviously more than welcome to use whatever products you like, and if you're happy with what you use that is great. However, I normally refer to the advice of Autogeek - they're the best in the business. Having said that, this is all dependent on how seriously you take detailing your vehicle, the cost, and most importantly the time it takes.
Using Vinegar to remove water spots - Auto Geek Online Auto Detailing Forum