I'm late to the conversation, but, got Experience.
First off: Agree with everybody to Watch Out for Home Depot extension cables. They look wonderful, nice and thick, and the labels say, "Ruggedized!"
But plastic is cheap, copper isn't.
Best place to buy decent extension cables that I've run across out this way is Harbor Freight. Their little display has a bunch of different extension cables and, importantly, How Much Current they can support. So, a 20' extension cable that's good for 20A has a lot thicker gauge wire in it (and, at HF, they actually
tell you what gauge the wire is!) than, say, a 5' cable. It's the voltage drop that matters.
I also note that the Really High Power cables have the 120 VAC connector with one of the blades at right angles. See
Wikipedia, and note the NEMA 5-20 connector. A 20A extension cord will have a plug with the blade at the right angle; the socket that one can plug into can accept the normal, straight up-and-down blade as well as the sideways one.
Code in NJ says that at least one socket in the garage has to be a NEMA 5-20. Dunno about other places.
But, a word of warning.. The OP is from Chicago. It can get cold up that way. And, before the car will charge, the battery will have to be warm enough to accept a charge. I drive around a 2018 M3; on days below 10F, plugging into a 120 VAC socket didn't provide enough power to heat the battery, so the rate of charge was 0 Miles of Charge per Hour. On warm days with that setup, one gets 5-6 MoCpH.
Which is why, if one can swing it, 240 VAC is so much better. 120 VAC @ 12A is 1440W; 240 at 12A is 2880W; but that NEMA 14-50 that can do 32A is 32x240 = 7.68 kW, more than enough to warm the battery up and get the car charged.