Ford's Drift Mode. It can make you look like a hero on camera, but it can also put you backward into a ditch. That's because while it can give an all-wheel drive car a shocking amount of tail-out action, it's not magic. Or at least not quite magic. Here's how it works.The actual Drift Mode is the result of some fancy mechanical systems and some cool electronics. But more important are the engineers and executives who were willing to hang their necks out as far as the RS can wag its tail.That's because it's one thing to make a fast performance car. It's something completely different entirely to make a performance car with a button that encourages you to go sideways. Very sideways. Especially after the pushback Ford got from Raptor owners who thought they could jump their trucks off of a second-story building. Fortunately, Ford Performance nitrous blue-lit the idea.The all-wheel drive system that underpins the RS is the Twinster torque-vectoring all-wheel drive system from GKN Driveline. Instead of a normal center differential, it uses a power transfer unit that sends power both to the rear driveshaft and to the front axles. It has a conventional open differential that sends power to the front left and right wheels - unless you're lucky enough to get one of the handful of limited-slip limited-edition 2018s - but there is no clutch up front to control power to the rear. In standard operation, the car sends 100-percent of torque to the front wheels.The trick is in the Twinster final drive unit. It uses two clutch packs, one for each rear axle, to control torque to the rear. The computer can engage either set of clutches independently, and that's what sends the power left or right. With them both disengaged, no power goes back. It can engage either one to send a tiny bit of power to one wheel, lots to one wheel, or any combination of left and right bias.The system can send up to 70 percent of the power to the rear wheels, and it can send all of that 70 percent to either the left or right rear wheel. The rear end - it doesn't have a differential like a normal car, just a ring and pinion to change the power from front-back to side-side - has a different gear ratio than the front. That means that when the rear wheels are engaged, they'll want to spin faster than the front. It's a method that promotes oversteer and makes driving more fun.It's that ability to send power between the rear wheels, combined with the rears spinning faster, that lets drift mode work.In normal cornering, the torque vectoring system sends power front to rear and left to right in all sorts of ways that make you quicker and smoother, and less understeery into a corner than your own ham-fisted driving style would allow. It can help keep you out of a hedge, up to a certain point. But we're here to talk about drift mode, not "Go Really Fast and Safe on Road and Track Mode".So you've arrived at a corner and you've decided that slow-in, fast-out is off the table, and you're not a big fan of proper apexes. Nope, you've got a paper cup full of water and some tofu to deliver up the mountain.You've already toggled drift mode so you toss the RS in and mat the gas. The GKN system's rear clutches engage and send a big dose of torque to the outside rear wheel, and a slightly smaller dollop to the inside rear. The fronts are getting by with about 15-percent each.That pitches you into the drift by breaking rear-wheel traction. The stability control isn't off, but it is relaxed. That lets you hang the tail out, but won't leave you completely high and try when you find out you're more like Itsuki than Takumi in a drift.The car keeps that rear and outside torque bias, and the rear wheels keep spinning. To make it even easier for you, the dampers are set to soft, as is the steering. That makes small corrections easier on your hands, and the soft shocks make it less snappy when you push too far or try and straighten up.Once you're done with the silliness, the car starts apportioning power the normal way again. Until the next time you want to make it go smokey and sideways.So that's how Drift Mode makes you look like Tanner Foust on the track. But it's not magic, it's technology. And in this house, we obey the laws of thermodynamics physics. Don't be the guy who tries it out on a back road and ends up in a tree. Oh, and Ford isn't the only one to use this system. A few automakers are using it, including the Range Rover Evoque. So where is THAT drift mode, Land Rover?