Four years after revealing the Vision S500 Plug-in Hybrid concept at the Frankfurt Motor Show, Mercedes-Benz
will return this September with the production S Class plug-in hybrid. That’s according to Car Sales, who claims a "S500 plug-in" will debut at Frankfurt 2013. From that we can deduce the eco-conscious S Class will be paired with the 455-hp S500 that will carry the S550 badge stateside. We’ll have to wait until the show to discover when Mercedes plans to roll out the S Hybrid, but we’d be surprised if it was any later than next summer.