Excellent question, and I'm not even sure if what I suggest can work, but I figure it might. I think this was the whole idea behind stablecoins like tether, no? Trade out of BTC of ETH if you wanted to capture gains, but didn't want to incur a tax, so you trade into another coin that is stable. Then when price gets low enough, you buy back.So what happens if you directly buy a Tesla with BTC, then turnaround and sell your Tesla car? Did you escape the BTC capital gains taxes?
Saying all this, I have no idea how the government can sit by and watch Tesla cars be purchased with something other than USD. Isn't there a mandate that no cash other than USD will be the official currency?