I wanted my 3 anyway. It's fast, and with some upgrades has very good handling. A friend of mine (former BMW owner) bought an S and said he'd drive it if it ran on baby harp seal oil. I think that, or a very strong desire to avoid fossil fuels, has to be your motivation; i.e., if you like the car, the savings is a bit of a bonus.

The extra cost to me vs. some other car was a $750 240V outlet install and the up-front expense of the car, which, at the time, was offset significantly by tax breaks. In California it costs me about $15 to "fill up" at home. I rarely do it at superchargers (only when on long road trips, which are rare). Quick math using those numbers at my pre-COVID driving level would indicate I'm saving $100 a month in gas vs. electricity (at $4/gallon on average). If I paid $10K more for the car it takes me >8 years to pay that back. Probably not a good economic call. A Nissan Leaf would've been much more economical, but I didn't want to drive a Leaf.

I will say that with gas at / over $5 in CA the savings are a nice bonus.