Smart Summon is one of the trick news features that's part of Tesla's V10 software update. It's perhaps the most anticipated feature of the update, but it's not really meant for racing in parking lots. Its purpose is to bring the car to you wherever you may be in a parking lot. However, that doesn't mean it can't be used for something more fun like a race.
You'll see a few races in the video. In the first race, the two vehicles stop because they get too close to a public road. In the second race, the Model 3 comes to a halt to give the Model X the right of way. You even get to see the Model X navigate a tight turn in the lot and it does so after automatically activating the turn signal.
Which vehicle is the overall winner in the Smart Summon race? Both, as each car seem to perform well autonomously (and they move far quicker than in earlier Summon versions) and neither hits an object in the lot.