Advocates of hybrid technology have often found themselves at odds with champions of diesel powertrains in vehicles. While they argue the finer points of fuel efficiency and highway vs. city driving, everyone could be happy with diesel hybrids. Although gasoline-electric hybrid vehicles have been around for decades, diesel-electric hybrid vehicles have been much slower to market. Given the higher energy density and now clean emissions offered by modern diesels, they still falter in stop-and-go driving situations. However, gasoline-electric hybrids have proven that city driving can be as efficient as highway driving, around 45 mpg, by using technologies such as regenerative braking, solar panels, and electric engines. It seems obvious to enhance hybrids by substituting a gasoline engine for a diesel one. Highway mileage improves and electric systems help with great city mileage.
- Full Hybrid
- Power Assist Hybrid
- Mild Hybrid
- Plug-in Hybrid
The aforementioned Mercedes model is a Mild Hybrid– look for other more complete implementations in the next few years. A few models have been announced by several automakers. In fact, General Motors has at least six concept cars as a part of their new Voltec platform, the Volt being the only concept currently slated for production. Each conceptutilizes different energy technologies. The Volt, of course, makes use of a plugin gasoline electric hybrid concept. But, the Cadillac Provoq sports an impressive hydrogen fuel cell as part of its hybrid powertrain.
Perhaps more interesting is the Flextreme
, which is being developed under the Opel and Saturn divisions. The Flextreme has the same Voltec technology found in the volt, but with a small diesel engine! The vehicle can make it about 40 miles on lithium-ion batteries before starting the diesel to recharge. It is a series hybrid, which implies that the power to the vehicle is driven only by electric traction. The petroleum-based engine is used to drive an electric generator, instead of directly powering the wheels. Also of note is the on board Segway storage and charging
Other diesel hybrids on the horizon:
European firms usually associated with excellence in diesel have been slow to adopt hybrid vehicles, although Volkswagen and Mercedes-Benz have been warming up lately.
So what has taken so long for diesel hybrids? Research initiated by the Clinton Administration developed diesel hybrid concepts that could beat 80 mpg in the early 1990s. However, diesel technology and hybrid technology are seen as relatively expensive on their own. The combination of the two has lead to prices higher than the market can bear. However, with a higher price being placed on energy efficiency and lower emissions, technology should sufficiently advance to allow these diesel hybrid technologies to trickle down to market.
This is a good article that briefly sums up the state of the technology.
2/17 Edit: fixed Flextreme hyperlink