Comments on: Diesel Hybrids Are On Their Way

By: Wheatridger

Wheatridger — Tue, 26 Feb 2008 02:06:46 +0000

Great news to my household, which just obtained its second VW TDI. For me, one big problem with current hybrids is that they use any gas at all. I much prefer diesel fuel for its lack of VOC emissions, its relative inflammability in an accident, and most of all, for its easy compatibility with biofuel blends.

Biofuels have been getting a bad rap lately based on the energy economics of corn ethanol, but soy biodiesel boasts returns 2.5 times its energy inputs to produce, according to National Geographic’s biofuels article of 10/07. That fact bears repeating in this context, IMHO.

By: Facebook User

Facebook User — Tue, 26 Feb 2008 00:59:28 +0000

I was wondering when we would get diesel hybrids. Sounds like it’s soon.

By: Robert Schwartz

Robert Schwartz — Tue, 26 Feb 2008 00:13:11 +0000

“the new diesel hybrids signal the end of German automakers’ participation in the two-mode hybrid technology jointly developed with Chrysler and GM”

I don’t know why there is any incompatibility between diesel and two mode hybrid. As I understood it, the two mode concept was first applied to crosstown buses.

By: frontline

frontline — Mon, 25 Feb 2008 20:43:57 +0000

I always believed that there was some merrit in a “clean” tiny diesel generator running at a steady rpm that could keep the batteries charged .

By: Edward Niedermeyer

Edward Niedermeyer — Mon, 25 Feb 2008 20:17:02 +0000

Engineer:Two different vehicles. The Bimmer gets 36.4 mpg which is a 50% increase over the 3 liter X5. The Golf gets the reputed 70mpg… you scared me for a second though…

By: Engineer

Engineer — Mon, 25 Feb 2008 19:37:08 +0000

Question for EN: The graphic shows a fuel economy of 6.5 l/100 km (36.4 mpg). From there to the reported 70 mpg requires a mere 92% improvement. Is that for real?

By: Brendan

Brendan — Mon, 25 Feb 2008 19:31:39 +0000

A diesel has a pretty broad range of peak efficiency. Like all ICEs they are less efficient outside of a particular range of RPMs, but that range is wider than gas engines. As a result, hybrids benefit gas engines more because of their narrower power bands. A mild hybrid diesel will give you most of the benefit of hybridization with out the complexity of a two-mode systems. Of course, there would be some savings with a two-mode vs. a mild, but consider how complicated those systems are PLUS how complicated the 50-state diesels are, and you have to wonder how you could sell such a vehicle at a profit.

By: CarShark

CarShark — Mon, 25 Feb 2008 19:02:57 +0000

Interesting. Veddy, veddy interesting. I’ve always thought that diesels and hybrids would work well together. The cost must astronomical, though! Wouldn’t that almost double the price of the Golf?

By: SunnyvaleCA

SunnyvaleCA — Mon, 25 Feb 2008 18:59:17 +0000

“too much torque for their own good”

I’ve never quite understood that kind of thinking. Just put a 2:3 gearing increase between the engine and transmission. Then, if your diesel engine produces 450 lb ft torque @ 1800 RPM and has a redline of 4500 RPM the transmission will see it as 300 fb ft @ 2700 RPM and a redline of 6750. Those revised figures closely match the characteristics of the 335i engine, so both of the 335i’s transmissions should be good to go.

By: Martin Schwoerer

Martin Schwoerer — Mon, 25 Feb 2008 18:44:56 +0000

Solar roof for pre-warming of transmission fluid? Exactly. These things have too much torque for their own good. (Yes, there is such a thing).

By: willbodine

willbodine — Mon, 25 Feb 2008 18:42:21 +0000

Considering the Diesel’s traditional thermal efficiency advantage, such a hybrid seems like a no-brainer.

By: hurls

hurls — Mon, 25 Feb 2008 18:34:06 +0000

I’m certainly no GM homer.. but what’s to keep GM from mixing their sexy new V8 diesel with the two-mode hybrid tech and making a similar leap. Beyond the cost, of course…