Honda Cars : Tech News: European Diesel Hybrids | 2013 New Honda Car Reviews 0

Here's a good article at Road & Track about what I thought was going to be the 'next big thing'....
Diesel-electric hybrid concepts from European automakers are all the rage at the 2009 Frankfurt International Motor Show.
Hybrids are great. Their clever interaction of combustion engine and electric motor can be optimized to exploit both means of propulsion.
Diesels are great too. Compared with gasoline counterparts, they offer a 25-percent benefit in fuel economy. And, unlike gasoline engines, diesels have gobs of low-end torque — just the thing for getting off the line adroitly.
Electric motors are great as well. They use no petroleum at all. And they too have gobs of low-end grunt, producing maximum torque from the first twist of the output shaft.
In fact, though, Europeans got on the hybrid bandwagon only lately. For a while there, they were most vocal in pointing out hybrid shortcomings of dual-propulsion complexity, battery weight and cost. Diesels, they propounded, were a much more rational engineering solution (especially when encouraged by fuel tax benefits in many European countries).
But there's an excellent argument that a diesel-electric hybrid is the automotive equivalent of wearing a belt and suspenders.
Diesels are more expensive than their gasoline counterparts, as are gasoline-electric hybrids. Thus, in a very real sense, a diesel-electric hybrid pays double for its technology. The costs of a diesel's necessarily robust construction, high-pressure injection and complex emissions controls must be added to the hybrid's electric motor, power electronics and battery costs.
What's more, a gasoline-electric mating is a fundamentally better one than diesel-electric. A gasoline engine's relative lack of low-end torque blends perfectly with an electric motor's instant twist. Also, a diesel's inherently abrupt startup and shutdown are a real challenge for engineers seeking transparent transitions, especially in Start/Stop, a key feature in the efficiency of hybrid interactions.
A diesel is super efficient at light load, when its air-fuel leanness extends to 50:1 and beyond. By contrast, a gasoline engine demands its ratio closely kept to around 14.7:1, and it's notoriously inefficient at light load. What's more, light load is the most efficient time for hybrids to run in pure electric mode. Whether off the line or at light load, gasoline and electric characteristics complement each other. Diesels and electrics are redundant.
Among European automakers, Porsche seems to sense this. The company has a quandary at the moment, whether to bring its highly successful Cayenne SUV to the U.S. in diesel form or as a newly developed gasoline-electric hybrid being introduced in Europe next spring.
The latter is quite an elegant system, its powertrain consisting of a 3.6-liter 333-bhp supercharged V-6 engine, intermediate clutch, 38-kW electric motor, lock-up torque converter and 8-speed automatic transmission, in that order. Think Honda Integrated Motor Assist with a clutch added between engine and motor. Disengagement of this clutch gives the Cayenne S Hybrid its pure-electric modes, including one called "Sailing," a coasting mode at speeds up at 86 mph.
Porsche's system is modular, and in time we can expect its recently introduced Panamera sedan to have a hybrid version — a gasoline-electric one.
No Zuffenhausen engineers are wearing belts and suspenders.

Source;
http://www.roadandtrack.com/article.asp?section_id=36&article_id=8379&print_page=y