Key to the future lies beneath camouflaged E-Class sedan.
Mercedes-Benz locking system engineer Santiago Pena Brossa touches his HTC smartphone gently against the door handle of the E-Class.
The camouflage-covered sedan's indicators blink and its rear-view mirrors swing out. It's open, but not ready to drive.
This car is still nine months or so from going into production. Which explains why this prototype's exterior is covered in an eye-baffling black-and-white pattern and its interior is hidden under rough-cut bits of what looks like black carpet.
While the visuals will remain under wraps for some time yet, Mercedes-Benz is ready to talk about some of the new E-Class's innermost technical secrets.
Mercedes-Benz will be the first to introduce the smartphone car key to market
It's a glimpse into the not-so-distant future of driving, because where Mercedes-Benz goes, others inevitably will follow.
The day the new E-Class goes on sale will be the beginning of the end for the conventional car key, it seems. In time it will go the way of the videotape, floppy disk and CD.
Pena Barossa promises Mercedes-Benz will be the first to introduce the smartphone car key to market.
The feature will be offered first as an option on the new E-Class, then spread to other models from the German carmaker.
There are some obvious downsides
The system relies on Near Field Communications, a radio technology built into newer smartphones and already in use in some countries by Visa and MasterCard for contactless payments. The ability to securely store encrypted data, either in the phone itself or its SIM card, is also required.
According to Pena Brossa, the Mercedes Me website will offer a facility for customers to check whether their smartphone can be used as a key. At first it will be possible to install only four "keys" on a phone, but the next step will permit any number. Perfect for car rental companies, says Pena Brossa.
There are some obvious downsides. A dead phone will mean not being able to get into your car. "You have a big problem," admits Pena Brossa, who points out that modern car keys are also useless when damaged.
Then there's the affection many feel for the good, old-fashioned car key. "The traditional customers, they love it," says the engineer.