The Tesla batteries are like 50 kwh or so. So if he has 2kw worth of gear, its enough electricity to mine for 2 days. This isn't the issue. Mining rigs, especially GPU are very unstable even when they are stationary, if he is driving around, going into bumps and taking turns, there is no way a GPU or 2 wouldn't crash right away.
Another issue is the heat. What is he going to do, leave the air conditioner turned on? He'd mine like 12 hours instead of 48hours if he had to leave the AC turned on. He needs to leave the trunk open, park it somewhere safe so the car or GPUs don't get stolen such as a private residence.
Only 16 MHASH With the Team Black Miner. But mining while charging is free money as long as your company is paying for it..