Our S100D and X100D both have 72A onboard chargers. We’ve been sharing a single 40A wall charger, but that gets old really quickly as you have to manage the charging vs letting two wall chargers manage if for you. So since I was going to add a second charger anyway, I decided to just upgrade the existing conduit and wiring to 100A. I could have simply added a second charger and a junction box to let the cars share the 40A, but decided to go all out.
Building code (here anyway) requires a disconnect near the load when the circuit is greater than 50A.
The conduit, wire, disconnect and breaker came to roughly $1000. The two HPWCs bump the total up to $2000. The permit was an additional $250 for a grand total of $2250.
If you are on a budget, you could get by with a 50A circuit and eliminate the $232 100A disconnect and about $150 for the heavier wire. This would knock $382 off the cost. In my opinion, that isn’t enough of a savings to warrant dropping from 80A of charging to 40A.