Driving home today, eastbound I-40, about 10 miles west of the Gallup supercharger exit. It'd been generally okay weather from Flagstaff which was 14ºF, and by Winslow it was in the 30s, but past Holbrook the flurries began and the temps dropped to freezing. Then just 10 miles from the Gallup charger, the snow got heavy, like a squall almost. Not sticking, but heavy. I was following an 18-wheeler who was driving carefully. Snow was swirling on the dry road; the truck was doing a good job keeping things clear for me. I stayed about 50-100 yards behind him. We were doing about 65 in a 75, no problems. Then the truck takes an exit and is gone. A minute later, snow starts sticking on the road. Soon, the left lane of I-40 is covered in snow, right lane is clear, but getting sticky. I slow down into mid-50s. A minute later, right lane is now two wide tire trails clear, but rest sticky and covered with 1/4 inch. And then within 30 seconds, now I'm at 50mph, and then suddenly the road gets slick, the whole right lane is covered.... This is where many things happened nearly simultaneously: • I let off on the gas very gently, but the regen kicks in, like you'd expect. • The regen kicking in turned out to be a bad thing because the laws of physics don't know about regen when it comes to cars and slick roads, they just know about cars, slick roads, and braking, and to the world this regen equated to braking. • My Model S begins losing traction. • Rear wheels get wobbly. • Now I'm beginning to fishtail. • All the while a Ford F150 that had been following me at a respectable distance has come right up behind me, and he doesn't seem to notice that my car is about to wipe out. • The Model S begins fishtailing, first left, then right. • Suddenly, I'm driving at 45 DEGREE ANGLE TO THE ROAD! I quickly steer to correct for this, and the car swings 45 DEGREES THE OTHER WAY! • I thought for sure my car was about to spin completely around and roll, or at least wipe out off the road or into the F150 behind me. • I make frantic steering corrections and I continue slowing down, car is right out on the very very EDGE of going out of control. • My wife was sleeping in the back seat, and she's awake now, observing what's going on. I told her to brace herself. • Car is wobbly like you wouldn't believe • I continue applying corrective steering, really fast, left, then right, then less left, then less right, trying to get car under control • Car is still wobbly, rear end feels like it is like 1/2 inch above the road surface, no contact • Can't tell if car is slowing down at all, feels like it is free-sliding on glass • Finally F150 truck behind me gets a clue and slows down and gives me room to recover • Fishtailing calms down, rear wheels have traction again • Front wheels are wobbly, trying to find their way • Car back under control • Heartrate, oh, probably 200 bpm All of above took place in span of about 20 seconds. Weird thing: within next 10 seconds, road surface became CLEAR, both lanes, no sign of snow, just wet. Clearly the snow trucks had been out and you could see the line of demarcation where they'd turned on the salt sprinkler, and things instantly melted. We take the next exit, the one for the Burger King that has the Superchargers, and park, charge, and assess what just happened. The car very nearly lost it. I figured, either crash into median guard rail or right shoulder guard rail -- I figured either was imminent, and that all was lost. Luckily, I was able to quickly regain control of the wild swings. Facts: 2013 Model S85, normal Michelin Primacy all-year 19" tires. Whew, is all I can say. Now: I am wondering if there'd been a way to instantly disable regen. I thought about popping car into neutral but wasn't confident of what might happen. But the regen definitely contributed to the near wipe-out. I'm curious what others would've done in this situation.