What do you guys think that pH balanced means?! I am pretty sure you don't mean 'balanced' - I have products where I specifically adjust (balance) the pH to around pH 12. I have products which are buffered to specific pH levels... but this is not what you guys are talking about. So why on earth don't detailers say what they mean - pH neutral?!
Swanicyouth is bang on though. Unless a product is specifically buffered (which is rare - Ive never seen a detailing brand make this claim), the pH will drop approximately 1 point for every 10 times dilution. So if you dilute 100:1, it will drop by 2 pH points. So pH 9 would theoretically be almost 7 (assuming your water is pH 7). pH 10 would go to about pH 8 and so on. A car wash shampoo (hand wash product) should really not be higher than this because it would be too aggressive for skin contact. So, for a high dilution shampoo, anything from about pH 4 to 10 is going to be neutral by the time you dilute it.
Another note for you is that a genuinely pH neutral product is likely more neutral than your water supply. I cannot be sure about the US, but in the UK, our water is predominantly closer to 8 than it is to 7. So your wash solution is going to tend towards the pH of your water supply, i.e. closer to 8 than 7 much of the time.
Basically, pH fear is ridiculous most of the time. If you are using a product neat, it matters more but the difference between pH 6 and 8 is pretty much zero in performance terms to you. Even going from 5 to 9 is making so little difference as to be indistinguishable to you. I would be inclined to redefine pH for detailers - less than 1 is strongly acid, 1-4 mildly acidic, 4-9 mostly neutral, 9-12 mildly alkaline and greater than 12 strongly alkaline.