Just in case you thought you could connect a couple of PalmPilots and cameras to your car and have it drive itself, I have some bad news: making a fully autonomous car is very, very hard. One of the people who probably knows this better than anyone is superboygenius Elon Musk, Like he did in , , , , and, . Oy, Elon, give it a rest, buddy.

In a , Elon said that fully self-driving Teslas are coming definitely, definitely this year, again:

“I think we will be ‘feature-complete’ on full self-driving this year, meaning the car will be able to find you in a parking lot, pick you up, take you all the way to your destination without an intervention this year. I am certain of that. That is not a question mark.”

That’s pretty bold, Elon. And, while it’d be fun to just believe you, I just don’t think I can.

Remember in 2017, he said this:

And, of course, that didn’t happen, because “Full-Self Driving Capability” — which I can only assume means —is staggeringly difficult, and, despite what Elon says, I’m not entirely sold on the idea that a car without can pull it off. If any car with current technology truly can.

If we’re going to be talking and thinking about autonomous cars, self-driving cars, robo-cars,…

Elon’s been saying a fully self-driving Tesla would be able to drive itself coast-to-coast as early as . Keen observers of the collection of events we call “reality” may recall that didn’t happen.

Really, I don’t blame Musk or Tesla for my skepticism. It’s not that I think they’re less qualified than anyone else, or that there’s fundamental issues with their tech, it’s just that the world is an incredibly chaotic place and building a driving robot capable of dealing with it all is staggeringly hard.

Sure, there’s companies like with already deployed fully-autonomous vehicles, but they’re all in geofenced locations—safe, controlled environments. That’s a very different ballgame from making a car that can drive itself in the messy, entropy-filled real world.

, you’d be able to fall asleep in your Tesla and arrive safely at your destination. We’ll see if that happens, but that

Hey, who likes riddles? Here’s one! What’s the difference between KITT from Knight Rider’s…

So far, Elon’s track record on full-autonomy predictions are somewhere around zero percent accurate. At some point, though, he’s likely to get this right. Maybe it’ll be this time?

I counsel against breath-holding.

We reached out to Tesla for comment, and will update as soon as we hear anything.