 I've owned my Mercedes C400 for less than a year.  Best car I've ever driven.  But like anything with astounding beauty and pedigree, it's simply too high maintenance, too cold, and now, too unreliable to be practical.From issues with components not properly installed on delivery, door seals unraveling a week into ownership, two recalls, a lack of comfort in the cabin so extreme I don’t drive the car long distances,  an engine stall in the street (sans key), service issues, and finally, total unreliability and failure; my C400 experience has been pretty disappointing.  I'd wait at least a few more generations before touching this model-- the glitches can be severe! Intuitive? It's smart enough to drive without a key within twenty feet, and stupid enough to stay in start mode and drain your battery, without any active attempt to start the car or even be present in the car for up to five (5) hours.  How smart is that.   Don't let your kids touch that button!I  found out.  After  meter parking  the car in NYC, and returning several times to re-load the meter and re-display my ticket inside the car’s dash window, locking the car every time, yet the car remained in active start mode until the battery died, with no error or warning message.  Smart would be something different.  If there is no active start (after pressing the start button) after a period of time--perhaps this super smart car should inform the occupant, via its intuitive  messaging system (no one but Mercedes can decode your car— so they tell me-- how's that for transparency), that if no ignition is attempted within  X period of time,  the power will terminate, and preserve battery life.  Now, that would be smart.  The C400 is not that smart. At less than 3500 miles, the battery died and two attempts (one of which was by Mercedes) failed to remedy the problem without dealer interference, some 60 miles and three days away.  Think about that.  You are  stuck in the middle of no where (to you, anyway), with a dead battery-- which can happen to anyone.  Mercedes roadside assistance fails to charge the battery or offer any other diagnostics on the car, and leaves you to tow to their dealership, where only they can remedy the issue.  Why?  The C400 apparently needed an extra long charge, longer than another motorist, a tow truck or their own roadside assistance could seem to achieve when they attempted to jumpstart the car-- the electronics wouldn't even activate but to unlock the doors and leave them disarmed.   A stalled battery is one thing-- and arguably my own fault.  But who wants a car so smart it won't take a charge from anyone but Mercedes?  While I believe the battery had, in fact, juiced itself into a coma, I also believe something went array with the car’s electrical and computer system, and the error was one that only Mercedes could clear. How’s that for holding yourself accountable.I had another safety issue with my Mercedes C400.  One morning as I was rushing to work, I got in the car (kids in tow), started her up, and reversed into the street when the car stalled.  Realizing I forgot my key, which was some twenty feet away, inside my house, it dawned on me how incredible it is that I was able to start my car and pull into a busy street, with no key in close proximity.    After a recent trip to the dealership, this was corrected, it seems but the service manager refused to disclose it had been an issue to begin with.My dealership (the worst luxury dealer I've ever encountered) insists there is nothing wrong with these cars and sales are robust, yet I have never seen another C400 on the road in my area.  Seems to me Mercedes has some work to do in refining this model. I hope Mercedes will proactively recall any C400's with a safety issue and correct any defects in its messaging/electrical systems, if found, of course.  Safety should be their top priority.  Back to Audi.  Tail between legs. Sigh.BTW, I offered my C400  back to the dealership (with less than 3500 miles). Not surprisingly, they passed.