I've only driven about 100 miles on these tires now, so these are really early impressions. It was sunny today, so these are only dry conditions.
The big discussion I often see is road noise because the OEM stock MXM4's have this dumb strip of foam which is supposed to quieten the ride and most other tires do not. I can say after initially driving on the CC+ that I don't notice any difference in volume of road noise between the MXM4's and the CC+. I think the CC+ sound "different" than the MXM4's because they have a different "note" when driven at any speed for lack of a better term. The MXM4's had this kind of muffled roar, the CC+ have a sort of hum. But one is not quieter or louder than the other to my ears.
What I noticed immediately is the difference in steering and handling. The CC+ are much, much more precise in handling. The MXM4's were always a bit vague and unresponsive, you would point the car where you think it should go and maybe you'll go there and maybe you'll go a couple feet to the right or left or where you wanted. The CC+ have a superior accuracy in steering response, I point the car where I want it to go and that is where it goes. Dry traction is worlds better, taking curves at speed on the MXM4's was always an exercise in wondering if I'll break traction and will the car start to drift and oh God driving on these tires feels like a suicide run sometimes. I can't wait to run these tires in the wet and snow and compare that to the MXM4's.
I want to comment on efficiency but I've only done a single round trip to work and back and I haven't been able to look at this in any detail yet. If I notice anything significantly different I will mention it after more time spent driving around.
The ride is definitely firmer on the CC+. I can feel road bumps more readily on the CC+ and in general the feeling on my butt is bumpier. The reviews are accurate there, these tires ride and feel firm. The 3 is already a car with a suspension tuned for a sporty feeling and these tires only magnify that feeling compared to the MXM4's. They are not tires for people who don't like feeling the road, I would suggest tires that feel softer like the Pirellis if you are not into the sporty feel. Note that I always kept the MXM4's at around 44 psi and the CC+ are currently around 41 psi and even with the inflation difference the CC+ feel noticeably firmer.
I find it hilarious that Costco quoted me a price of $1100 to replace MXM4's with another identical OEM stock set but only $850 to get me this set of CC+ when the CC+ are so clearly superior. That stupid strip of foam is apparently worth $300 and reduced performance in all road conditions. Michelin is ripping Tesla off here big time.
OEM tires are always more expensive, doesn't matter if they are actually good or not.