With smog control, mileage and drivability pretty much handled in new car engine designs it appears the that sludge is the next challange. The answer is going to have to be design, maintenance schedule and quality of fluids and filters. There just may not be one solution that will fix everything. I see why you are making this post. In an imperfect world, Auto-RX is a good hedge against future problems. I just finished a one pass cleaning on my turbo Volvo and it even cleaned the stains off the dip stick that I couldn't scrape off. I'm confident that the inside of the engine that I can't see has been cleaned up, too. With Auto-RX I don't think there will be a sludge problem.
