Does this car have an emergency release?

You have no emergency release as you need to release the electronic parking brake and put it in neutral and both need power to operate, and the key has to be turned on. To move it without a key will likely require a dolly system to load it.

That's Mercedes for you. What's worse is how many others are going the same way and making the cars into rolling computers with no mechanical back-ups.
The absolute worst vehicles I've seen like this are fire equipment. A vehicle that, when needed, must work, and they install computer-controlled valving and pump controls. One local department bought a fancy new engine with all the electronic toys on it, they made it into a big working structure fire and the system malfunctioned and they had no way to fight the fire! Ended up calling in some of us old school folks to fight the fire. They ended up running it for 6 months and it failed two more times, then they shipped it back and had the electronics stripped out and manual controls put in.