I believe the formula changed sometime in the last year or two. The stuff you commonly see at Wal-Mart or the generic part stores is not the same as it was in years past. It still works, but I don't believe it is as strong.
I'll politely refute your assessment. I have used it for 25 years and believe it is as strong as ever. I use it on everything, even non car stuff. At almost $4 for a spray bottle, it seems to me that it can be purchased in bulk. Several years ago, I used to buy half gallons of it at Wal-mart, the Zone, AAP and others to refill the spray bottles, but haven't seen them in a long time.