It was roughly four months ago when we first heard of an upcoming Mercedes-Benz S-Class plug-in hybrid via some leaked slides at a M-B presentation.

Now, Mercedes-Benz has officially confirmed that its flagship S-Class will indeed get a plug-in hybrid added to the lineup in 2014 and the latest intel says that the plug-in hybrid will get its grand debut at the 2013 Frankfurt Motor Show this September.

2014 S400 Hybrid

2014 S400 Hybrid

Mercedes-Benz’s next generation flagship S-Class was introduced at an elaborate event in Germany, but the S500 Plug-In Hybrid wasn’t present.  That's because its launch is later than the rest of the new S-Class lineup.

There are still only limited details available on S 500 Plug-In Hybrid, but we do know that its world debut will be in Frankfurt this fall and that it'll emit less CO2 than it s nearest competitor: the Porsche Panamera S E-Hybrid

As Autocar reports, "...the final CO2 figure of the S500 Plug-in Hybrid, as the model will be known, will be just 70g/km in order to trump the 71g/km figure of current lowest CO2 emitter in the luxury saloon segment...Economy is expected to be above 90mpg on the combined cycle."

There's no word on pricing for the plug-in S Class, but as is the case with the rest of the S-Class lineup, most potential buyers aren't worried by price.

We'll have more details on the S 500 Plug-In Hybrid as its debut in Frankfurt draws near. Source: Autocar