Diesel Hybrids

[tractorboy]

Why are all hybrid cars petrol based?
With diesels giving very high MPG figures - the best I could find was the Kia Rio 1.1 CRD which is meant to give 88 MPG. A Golf 1.4 TDI gives 74 MPG combined. (UK figures)
Wouldn't a hybrid system raise these figures by 10 - 20%? a 100 MPG car should be possible.
I'm guessing there is probably some very good reason why it isn't done. Cost and weight are obvious factors but is there some killer point that I'm missing?

[Ol'Man Driver]

Peugeot 3008 HYbrid4 is a Diesel Hybrid

[Jayemtee]

It makes a lot of sense on paper to have a diesel hybrid. I would guess it would be harder to market, especially in the USA. They do sell well in larger applications such as a city bus.

I also don't see a lot of R&D in the gasoline hybrid market. Pure electric seems to be hogging the drawing boards.

[Ludercrz]

most hybrids are electric or gas like the prius where the gas engine kicks in at higher speeds, but honda's IMA piggy backs the gas engine. if they had that piggy back system on a diesel engine i think it would work really well.

pure electric cars have been working since the 90s, but the "Gas Companies" have put a stop to it.

watch these vids. (Narrated by Martin Sheen lol)

[Tyrod]

The newer style of hybrid where batteries supply current to an electric motor which in turn drives the wheels and an external power supply (such as a diesel engine) only charges the battery would benefit from highly efficient engine designs.

What makes gasoline so great as a fuel is the wide range of engine rpm that it can be used at while still delivering reasonable fuel economy. If you no longer need that wide range of rpms then using a more fuel efficient engine design such as a diesel engine is advantageous. Think about it. In the newer hybrid model the engine is only a generator. It need only run at 1 specific rpm to charge a battery. A diesel or gas turbine that only needs to run at 1 specific rpm would be extremely efficient. Of course, the engine would only run as required by battery charge condition.

[Varmint]

Primarily $

The hybrid electrical motor and battery system costs quite a bit of money. Diesel engines already cost significantly more than petrol-powered designs. Adding the cost of a hybrid drivetrain to the diesel raises the final price outside of the the range of profitability for the manufacturer. Ever wonder why hybrid models like the Civic and Accord tend to be equipped with most of the options from the EX, rather than an LX? That's because the profit margin on those options helps to compensate for the cost of the hybrid system.

In addition to the cost issue, electric motors grant the majority of their thrust down in the low rpms. Well, diesels are already pretty good with the low end thrust. Turbo-charging helps extend the rpm range much better than an electric motor can. So adding electric power to a diesel engine doesn't really accomplish much, assuming the diesel engine will remain the primary source of thrust.

Year ago, Honda was working on HCCI engines. (Basically, petrol engines that combust via compression... like a diesel.) Those engines have a strong mid-range, but offer little at the top and bottom of the rev range. The engineers hoped that electric motors would solve the low-end issues. For whatever reasons, it never worked out.

Green Car Congress: Honda Making Significant Progress on HCCI Engine for Hybrid Application

[GoHuskies]

Cost.

Hybrids and diesels are already niche products in most cases so adding additional cost with only marginal gains is not an economical choice for most automakers. The cost to develop then certify these cars for various world markets would likely eat away any profits since few people are going to spend an additional $2000 or so on a Jetta TDI if it only saw a small fuel economy increase from a hybrid assist system.

Auto-stop function at a light is one of the hybrid aspects I think we will see on many new cars. Kia will introduce auto-stop as part of a fuel economy package for the next Rio and Mazda was a smart-stop system in the works for regular gas cars as well.

[sleighman]

Big Oil, I personally beleive that Big Oil is the main reason a huge precent of our cars don't get 50,60,70 + miles per gallon. We have had the ability to have this for a long time but corporate greed stands in the way.

[CR-Z Canadian]

^ And California Emissions - without a catalytic converter, your mileage also goes up.
And the safety goblins - the extra weight you have to lug around, to keep you from killing yourself, tends to kill fuel economy.
But Varmint has it right - the diesel engine does its best work overlapping where the electric shines - low end torque. To make them perform better across a wider range of driving demands, most are turbocharged. So, as others have stated, you get the cost of the diesel, the hybrid powertrain and battery, and the turbocharger, all for what? A diesel VW Golf got 60 mpg twenty years ago, without the hybrid components to add cost and potential failures.

Tyrod's comment is right - a clean diesel "range extender" generator on top of a plug-in electric powertrain is the likely way of the future. Until, that is, a viable fuel cell and supporting infrastructure can be created.

[Ecotune]

great vid ludercrz.. I own it! Everyone should watch it