The fact that people who bought a car that didn't self-drive now have one is probably the most novel aspect. Lane keeping, adaptive cruise control, parking assist, collision avoidance, etc are all features in other vehicles as well, slowly trickling down to more models each year.

Does it have to be? (serious question).

Right now, IMO, we just need more self-driving cars in general to move the whole concept in terms of acceptability and availability. There is certainly lots of room for innovation, but for now just more product selection alone is valuable.

I'm not being facetious, just curious. Is this novel in any way or just an expansion of technology on the market?

I think the part that's constantly fascinating about the Tesla cars is that these features are being delivered as software updates. This would be like a software update that switched your phone from 3G to 4G.

Although I agree it's a cool way of rolling out features it's more like buying a phone with 4G capabilities but it not being rolled out until a software update; It's always been possible in the cars they just got the federal approvement now.

In one sense, yes—though I would also compare it to some of the cool hacks NASA does getting orbiting telescopes and Mars rovers doing new things they weren't doing before. All the sensors and motors and antennae are there, but a firmware update can put them together in new ways to enable entirely new high-level behaviors that weren't being considered or planned for at launch.

An example in this vein: imagine a firmware update to a wi-fi router to give it MIMO support. A MIMO antenna isn't any different than a regular antenna; the difference comes in the baseband firmware doing clever-er math to pull out overlapped signals, spacially model their sources, and modulate its own output so the signal will constructively interfere for best performance at the destination.

Ultimately, I think it's not very different.

In a Cliffs-notes sense, both vehicles seem to offer an autonomous driving mode in normal conditions. Like any other competitors, they both have a few unique features that are neat but don't really change the overall experience exponentially.

To be clear, I own neither a Tesla or a Mercedes currently and I'm basing this just on looking over the specs, but they appear to be fundamentally comparable.

Mercedes requires hands-on for steering. The Model S is nearly capable of fully hands off. Model S can also change lanes with a button.

For one, it is being deployed via a software update to vehicles already sold.

I don't think I've seen automatic lane change outside of Tesla.

Mercedes' version requires the driver's hand to be on the wheel during steering. If not detected within 14 seconds it is disabled. Tesla's version (despite their CYA language) requires no hands on the wheel, UNLESS the system loses sight of road lines OR a tracking car in front.

In addition the Mercedes' system can't change lines automatically.