Very impressive. Beware, however, that the article states that the first leg was downhill. It would be nice to see the altitude change. The bladder control is more impressive...geez.
550 is no small feat, but since nobody has set criteria for these attempts, some have been done under conditions that balanced for environment like Bjorn's feat and this one which used altitude and wind to his advantage. No matter how it is done, just sitting in a car for over 20 hours with no HVAC and driving 20-25 mph is grueling on the body and an achievement all in itself.
Maybe there should be two classes for these records, Balanced External Environment, and Unlimited.
I would think the elevation drop right at the beginning would be less efficient than later in the drive. At the beginning the batteries are charged to 100% and the Tesla charging system is not as efficient when the batteries are near 100% then when lower. So some of the regen at the start might have been lost. Though it probably wasn't much all told if he made 550 miles.