I have a fairly new house, and 100A service. I had a friend who was an electrician wire it for me. Fortunately, an attached garage, so drill a hole between basement and garage with 50A service. To avoid actually hooking up the charger, I have a NEMA 14-50 socket, and connected a “range cord” (Stove plug cable) to the charger unit (also rated for 50A). It would also allow me to use the protable Tesla charger instead if there’s a problem with my wall charger. Total run is about 30 feet.
You will definitely have to pull new wire. The cable to the garage is pretty thick. You might get by with a 30A service. 50A circuit means 40A continuous draw is allowed. (80% rule) My Tesla Model 3 can charge 240V 40A (Or maybe it’s 48A, never going to try). The Tesla charger has a rotary switch to set max amps, up to 80A for Tesla luxury models. I’ve seen a few houses in the area with a kitchen stove in the garage, presumably ethnic families who put their “spicier” cooking out of the house. (Some more expensive houses come with a separate “spice kitchen” nowadays.)
Nominal charge rates - 40A gets me 56k/hr, 32A about 48k/hr. (Standard 120V 12A gets 5k/hr on a standard household 120V 15A circuit)I have the vehicle set to charge at 1AM when plugged in. Usually the only things that could be going at that time are the hot water heater, AC, and maybe the fridge or freezer. I make a point of not cooking or running the dryer, dishwasher, or oven after 1AM. So if you ran a 20A 120V off your existing panel it would charge 16A 120V which would be about 7 or 8km/hr (4 to 6mi) just, anything else - lights, garage door opener, etc. - you risk popping the garage breaker.
I have seen some setups discussed online where two outlets in the garage (or outside wall) could be twinned to produce 240V if they were fed from opposite sides of the panel, but if your garage panel is fed by a 20A circuit it’s probably a plain 110V feed.
After 2 years I had an episode where the main breaker flipped in the middle of the night - not sure why, I don’t think there was 100A draw on the house, I don’t even think the car was charging at the time - but I’ve set the car now to charge at 26A which adds about 38k/hr. and never had a repeat episode. Max range at 80% charge is 400km (240mi) so most of the time, the car is ready at 8AM. If I’ve really drained I can start it earlier. Or get by for the day with only 70% charge or 300km range, catch up next night, etc…
The cable is fairly thick. You want a professional to do it, and be sure everything is screwed down tight! You are talking an immense amount of power compared to anything else in the house. You could probably get away with a 240V 30A circuit (24A continuous draw) if that’s all the panel will take, if you let the car charge longer, and don’t run the dryer at the same time.
If you can’t run in a trench under the driveway, can you run in the air? Ugly, but simpler?