I’ve had a P85D for over three years and a Model 3 for six months. I also have two young children (6 and 3).
There is no question the Model 3 is a better overall vehicle. Faster MCU, AP2.5 hardware, faster charging at the same amp, and more range. The P85D will be a bit faster than a Performance Model 3, but with small children facing rearward, you’re not going to be doing insane launches as much as you’d think.
Also, the Model 3 isn’t particularly small. The length and width of storage is only a couple inches smaller. The hatch and height are where the Model S shines. Unless you have a crazy big stroller, they’ll be fine in both.
The Model S has a couple inches more width in the back seat. It can handle three across if you get slim car seats, like the Diano Radian. More importantly to me, the Model S can handle two car seats and a small adult in the rear. The Model 3 can almost do this if the adult passenger holds their breath. It’s the single biggest drawback to the Model 3 with two children.
The auto lift gate on the Model S is great when your hands are full.
It’s a really close call for me, particularly keeping a family in mind. Now that my kids are older, the 3 is fine. The hatch on the Model S is convenient for changing kids in the back or hauling more stuff. But I’d definitely check out the size of the Model 3 trunk before deciding.
The Model 3 definitely feels fresher. It drives more sporty and fun. The Model S feels larger and more sturdy. It doesn’t feel as nimble but it makes up for it in a commanding feel.
AP1 has had a great run with feature parity, but I suspect we’ll be seeing a divergence with AP2 taking a noticeable lead in the near future.
Honestly, you can’t go wrong with either but I’d consider the non-Performance versions as well considering how much you’ll be hauling a baby and associated gear.
Congrats and good luck! There’s really no bad decision.