M3 comes with supercharging standard. But to use superchargers free for the life of your M3, you have to pay, mostly likely $2K, for such an option. Elon only said M3 comes with supercharging standard, he was very careful not to say M3 comes with free supercharging for the life of the car. Quite a few people are able to read into what he said between the lines.
Elon also said he expects average M3 price to be around $42K. I dare to offer he figured most people would add free supercharging and auto pilot. These 2 options together would add $4,500 to the $35,000 base price. Add documentation fees and pay for your favorite color ($1,000 to $1,500) now you have a ~$42,000 very capable utilitarian fast car.
If you want leather seats, auto lift, premium interior, premium stereo, dual wheel drive, bigger wheel, better performance ; it will cost you. But you can have a very luxury compact sport sedan if you have the money.
Even if you don't have deep pocket, I agree with Elon M3 still is the best car you can buy with $35,000 (even without free lifelong supercharging and auto pilot, that is).