For decades, Mercedes-Benz sold only two passenger cars. Now, the automaker is promising 10 different electric cars.

Although the Mercedes has not revealed plans for all of them, spy photographers have recently captured a large electric sedan from Mercedes-Benz testing at Mercedes's headquarters in Sindelfingen, Germany. 

The spy pics were published by Motor Authority.

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In line with Mercedes-Benz's naming convention and statements from company executives, observers expect the new sedan to be called the EQS, sitting parallel in Mercedes-Benz's lineup with its flagship S-Class.

Previous statements from Mercedes executives have hinted that the EQS will go on sale in 2020, likely as a 2021 model.

It is expected to ride on Mercedes's dedicated, modular electric-car architecture, dubbed MEA. At the same time, Mercedes is separately developing a new gas-fueled S-Class sedan that will ride on a separate rear-wheel-drive gas platform (MRA), and debut around the same time.

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The EQ chassis sits a little higher than the basic S-Class to allow space for the large battery packs under the floor, but it has a much more steeply swept windshield and sleeker profile.

A high tail indicates it could be a hatchback, perhaps like the Tesla Model S, its target competition. It could, however, be just part of the prototype's camouflage.

Among the 10 electric models Mercedes has said it will deliver, the EQS represents the third passenger car, after the EQC small SUV and the EQA small coupe.

It has also revealed prototypes and specs of two commercial electric vans, and is expected to offer a small electric sedan the size of the C-class.