The A/S3 definitely looks promising. Michelin is claiming dramatic increases in summertime traction while maintaining the treadlife and winter traction of the A/S Plus. I've driven them on our test track and was impressed with the grip level. We have not crunched all the numbers yet from our instrumented testing to say exactly where they stand as far as grip level.
It's impressive that they even dare to compare their all seasons to summer tires. They may even beat out some of the lesser tires in the summer category, certainly the cooler the weather the better chance they will have. I do NOT think they will equal the dry grip of the true class leaders, like the Pilot Super Sport.
I do think that Michelin has some wizardry in their tire carcass construction as far as managing contact patch shape, and it's allowing them to really step up the level of grip without needing a softer compound. They haven't come out and said how much of their performance gains come from which technology. But with the PSS and AS3 both touting their enhanced contact patch shape, and both breaking the mold for their categories as far as grip level, I suspect that is the 'special sauce.'
I have accepted a new position at Tire Rack and am no longer in the sales department. firstname.lastname@example.org
is available to assist with M3 questions.