I've been using a 50% mix of alcohol & filtered water and find it works well on road grime as well as around the house. The vinegar sounds like a neat addition. In the past I've also used Bon Ami on the exterior only to remove oils and winter salt sludge and found that it works great. It WILL scratch your mirrors, though.
Since I have a newer car, I'm going to try the vinegar at 50% first and then full strength to remove some water spotting.
Since I have a newer car, I'm going to try the vinegar at 50% first and then full strength to remove some water spotting.