Mercedes to go plug-in hybrid route

The current S-Class.

Strict new emissions regulations in Europe is prompting Mercedes-Benz to develop plug-in hybrid versions of its mainstream cars, writes Brian Byrne.

The company plans to have 10 plug-in hybrids across its fleet by 2017. The first will be the brand's flagship car, the S-Class.

All carmakers are required to meet low average fleet CO2 levels by 2020. Premium brands find this tougher, as their cars tend to be generally larger and more powerful.

Mercedes-Benz needs its fleet emissions to average 99g/km of CO2 by 2020, 26 percent less than it was in 2013. Electrification through hybrid systems is the only way they can achieve this.