Hi and thank you in advance for your help. W213 year 2016 here, Keyless Start but not Keyless Go installed. Well, it looked obvious to me that if you can start the engine without inserting the key you can also enter the car that way; but no, Mercedes offers you the possibility to start the car that way but you do have to look for the key in your pocket and to unlock the car using the key, which bothers me a lot.
Anyway, the question is: why is the car, once started, able to be driven without the key inside the vehicle? I often leave the engine running while leaving the vehicle for a few minutes (for buying a can of juice from a little store, for example). A thief really can go with the car even if he doesn't have the key, which surprises me a lot.

That is not possible in my MY18 with KeyessGo. If the fob is not inside the vehicle, the transmission will not change from park.

Hmm, I know this is possible in other brands, but not sure about the W213. I now must check this, and report back soon.

My other car, a 2016 Grand Cherokee, can not be driven if the key fob is not present, and this is normal. But a Mercedes can? It worries me, I don't know if this happens to your cars as well or if I should take it to the service.
I wanted to make an Arduino project in order to start the engine from my mobile phone, but if the car can be driven without the key fob, it will be pointless.

it is possible in my car.

My car displays a message about the keyfob not present.

And I suppose you can not drive your car when the key is missing. Mine shows "not detected" as well, yet it can still be driven.
Would it be a diiference between the US and the European cars? Mine (sold in Germany) and Egonvdv's (Holland/France) can be shifted from P, while ua549's car can not. It would be interesting to know. As I have been told from the dealer, the remote start possibility is also not available in Europe, while it is in the US.

It is not possible to drive our E400 or E450 unless the key fob is in the car with me.

Just tried this out on my US-spec Mercedes E400 Coupe. A couple of observations:

1) You can remote-start the car from the Mercedes Me app, but only if it is locked, the proximity sensors do not detect any object, and you have more than 5 gallons in the tank.
2) No one will be able to take away the car because it is locked. Also, the moment you open the door (with the keyfob in your pocket), the engine stops running and you will need the keyfob with you to restart it.
3) Then, I started the car with the keyfob on me, stepped out of the car, and put the key some 10 ft away. Indeed the car said key not detected, but it let me open the garage door, engage Reverse from Park, and go on my merry way... So, if I were to leave the car running with the doors open while I go to the store (you can't lock unlocked doors if the engine is already running), anyone could drive it away. A sobering realization I was not aware of!
4) If you stop the engine without the keyfob nearby, you won't be able to restart the engine, but by then a potential burglar can have driven your car anywhere where they can disassemble it for parts...

This reminds me of some ingenious car robberies happening in the UK using a radiofrequency relay and assuming many people leave their car keyfob near the entrance when they arrive home. An example is shown in this video (also from the UK)

So, it seems 2018 BMW 7 series have the same issue. I wonder why some W213/C238 E-classes cannot be driven without the keyfob present, while others can, like mine... Bummed...
Obviously if you are driving along and the keyfob dies, you don't want the engine to shut down, but if the car is in Park, it should not let you disengage Park if the keyfob is not present...

once car is started i can drive it without the key, until i switch off the engine
it does indeed show the message that key is missing

My local car wash has a huge sign telling owners to take the key until at final drying station. They had several cars stolen with the keys still in the car.

So, as I see, my car is not the only one to allow driving without the keyfob (while I see there are other cars which don't allow that). It is confusing and most of all it is annoying and quite irresponsible. What if my 10 years old son, or other people I leave in the car, starts driving the vehicle while I am going to the restroom for 2 minutes, keyfob in my pocket? We didn't know about that and I am sure a lot of drivers are not aware about it. Why can a car be driven without its key??
My car does not have the keyless entry option and I can not lock the doors using the keyfob while the engine is running. It does not matter anyway, @e400c, because even if the doors are locked, it is easy for a thief to break a window, step into the vehicle and drive it. The value of the car is still high no matter if a window is broken , you can replace it quickly. I usually leave home around the same hour and I usually start the (other) car's engine 10 minutes before leaving, which would be more than enough time for a thief to break a window and steal the car. With the Jeep is not possible because the engine will stop if a door is open or if the brake pedal is pressed without the keyfob's presence, but if I remotely start the Mercedes it will be surely an invitation to theft.
Thank you for the video, e400c!
I am still pissed off about the Mercedes' approach on this matter. I will complain about that when I will be leaving the car at the dealer for some minor issues (the GPS antenna is not functioning; the perforated metal sheet on top of the dashboard vibrates), next week. But I don't have big expectations..

To clarify, would you not shut the engine off, with your 10 year old in the car, before going to the rest room? If so, there's not problem. If not, it's the same as leaving a car running with the key in the ignition. It does appear that there are differences from one model or year to another, in exactly what a car will do if the key is removed. And I agree it would be best if the car, running, would not shift into gear without a key nearby. But I have owned cars with keyless fobs since 2006, and AFAIK all of them required the key to start, but not to change gears or drive once started. I never considered that a real problem (although, again, I think it would be best if it would not shift gears either, and would consider that an additional feature, not a bug or problem without it).
Well, typically a car, once started (by screwdriver in the ignition, wire-jumping, key, whatever) can then be driven, not requiring a key at that point.

Someone above mentioned that the Merc engine will stop when a door is opened, but I don't know that to be true.

The engine will stop when a car that was remotely started is unlocked. The door does not have to be opened.
In Florida it is illegal to leave car with the engine running unattended. If you leave a child in the car alone (engine running or not) you can be charged with child abuse.

This is a list of states where it is illegal to idle your car that I kept before I retired: Arizona, Colorado, Connecticut, Delaware, District of Columbia, Georgia, Hawaii, Illinois, Louisiana, Maine, Maryland, Massachusetts, Minnesota, Missouri, Nevada, New Hampshire, New Jersey, New York, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Texas, Utah, Vermont, Virginia, Wisconsin and Wyoming. It is a protect the environment regulation/statute.

The key is the proof of the permission to operate the vehicle. Since I go to a local shop and take the key (the permission) with me, it is supposed (or it should be) that only me, the key holder, may operate the vehicle, which does not happen; some other persons may operate the car as well, without having the key. But this would be a very long discussion with persons who think the opposite and I don't want to start it.
What's crazy is that I have checked today another two cars: first, a friend's BMW 7 series which allowed me to drive even if the owner had manually locked me in the car from the outside. Second, and that is my fault my own Grand Cherokee, which acts just like the Mercedes (even if I was damn sure it wouldn't). When I remotely start the Jeep, the engine stops if any door/trunk is opened in the absence of the keyfob or if brake pedal is pressed. But if I start it normally, it allows any person to "steal" it.
Yes it can be considered as an abuse to leave the child unattended in the car, but it depends on the circumstances (like the time spent alone, the age of the child, the interior temperature and so on). Also, I know that it is not environmentally good to have the car remotely started. Yet, such alarms and car options are still available on the market. I personally use the remote start firstly to protect the engine (each car has less than 35K miles) and secondly for my comfort. At work, I almost always manually start the Mercedes a few minutes before leaving (it is parked just 2 meters from my office door) and return to the office; starting now I won't do that anymore, you never know when somebody is waiting for that opportunity.

Giloffice, No argument with any of that. I do notice that you specifically let the car idle several minutes before leaving. I've also heard you need to give the oil a chance to distribute, and of course you should never use maximum acceleration on a cold engine, but have always considered 10-15 seconds sufficient to circulate oil and make the car ready to drive, at least to get out of the garage/driveway/parking lot and to the road. I gather you have a different opinion on this? Just curious about your and others starting practice.

Guess what? Even if I let the car idle for up to 10 minutes (after that, the Jeep, for example, turns off the engine if remotely started), I still drive very calm until the temperature reaches the optimal point. Not in terms of speed (I don't drive slow), but of acceleration. I do care about the environment (turn off the lighjts when not needed, drive just a little over-speeding, turn off the water while brushing my teeth or while shampooing, clean up the camping lot if somebody before me left some garbage etc), but in order to have a good engine I even sacrifice a little the environment, I admit. And yes, you are right, of course, the engine heats up way more rapidly driving calmly than idling, and I am talking about diesel engines here, both of them.

I remote start my car to cool it when it has been parked outdoors for a lengthy period of time. Typically I'm closer than 2 minutes away. Other than that I never leave the car with the engine running.

Wise decision, grasshopper!

This is currently a problem with all keyless ignition vehicles, but there is a very simple solution that all manufacturers including Mercedes Benz could implement with one line of computer code.
All keyless ignition vehicles should require the key fob to be authorized again at the time the brake is applied when the car is being put into gear. If the key is not in the car at that moment, the gear shift should be locked, thus not allowing the car to BEGIN driving. This is a FAIL SAFE solution to avoid ever allowing anyone to drive off without their key and will reduce theft. Please sign my petition !

https://www.change.org/p/how-smart-i...off-without-it

I was dropped my car at a valet parking area and I exited the car with the engine running. The valet tried to move the car, but couldn't put it in gear. I still had the fob in my pocket.

Ua549, What model of Mercedes does that?

It’s in his signature slr.

Pardon the non-Mercedes information, but thought I'd try this on my 2017 Acura RDX, and once started using the key, and then removing the key from the vehicle, nothing stops anyone from putting the car into gear and driving it. (Petition signed) As a helpful measure, removing the key from the car and closing the door sounds a long beep and displays a message on the dash that the key is missing. Likewise when putting the car into gear with the key absent.

So, what's up with ua549's car? Is it different than apparently all other recent MBs? Did the valet accidentally turn the engine off first? Did the valet forget to use the brake? Are there any other questions?
(Sorry about "all other recent MBs"; I never saw the above comment from JDPEClassUK, being over to the right like that. So, maybe a US-only thing?)