There are several diesel-electric hybrid cars on the market, in the EU. The one that is regarded as the best at present is a Citroen, bless their weird little hearts. Should’ve known, lol. I hate that they’re no longer sold in the US. Very innovative, not at all afraid to be different and they’re good at it. The worst ones are also French though. Peugeot. Pieces of crap from what I read. Par for the course there, too, lol.
Early technical review of the Citroen “Hybride” diesel-electric:
http://www.autoblog.com/2006/01/31/psa-peugeot-citroen-unveils-diesel-hybrid-technology/