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Hybrid cars
A gallon of gasoline contains 125,000 BTU's of energy (or available work). A gallon of deisel fuel contains 155,000 BTU's. With almost 25% more available energy per gallon, diesel seems like an obvious place to look for efficiencies. With either fuel, a hybrid will be limited to extracting a defined amount of potential and kenetic energy from every gallon in the most efficient way possible. It is a balancing act between trapping, storing, and re-using energy and the additional losses experienced by doing so.
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"With almost 25% more available energy per gallon, diesel seems like an obvious place to look for efficiencies. "
I'll paraphrase a statement made earlier this year on this site. "GM singlehandedly ruined the diesel market in the US for decades."
The marketers know that many are still afraid they're all boat anchors like the 350 GM diesel.
Dave
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That is true the old GM diesels were out and out junk!! I have even tried to modify them with no prevail, added a turbo and other mods still JUNK.
But the new diesels out to day are excellent (though still not sure about the GM line) the Ford and Dodge as well as VW, and Mercedes are really great engines.
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I had some visitors from overseas this summer.
In the course of touring them around Toronto one of them commented about how expensive taxis must be here. This comment left me a little bewildered at first. How can seeing a taxi driving down the street give you any indication of cost? When questioned about the comment the answer made it all very clear.
If they can afford to throw away a big North American car every couple of years after paying big bucks in gas & repairs they MUST be bringing in lots of money in order to be able to afford to do it and still make a profit.
When I asked about taxis "back home" the reply was "Mercedes Diesel sedans, ALL of them." Apparently they run these things for sometimes in excess of 20 years and just rebuild them as a routine thing every 600,000 kilometers (372,000 miles) or so.
It is not uncommon I'm told for these things to run 20+ years and rack up several million kilometers before they are retired, and even them there is a long line of people who want to buy them for personal use.
Now THAT is a USED car.
Best of luck.
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The fact that diesel has more BTU's per gallon vs. gas is irrelevant. It takes more crude to produce one gallon of diesel than it does one gallon of gas. What is being refered to here is energy density of a fuel and not energy efficiency of a motor - the amount of work you can get out of a unit of energy.
If all are right the most "efficient" would be a hybrid diesel car. I am not aware of any of these units being produced - I am sure there is a good reason althought it may not be engineering / mechanically related.
In countries where gas and diesel are more expensive (as a proportion of disposable income - not the US / Canada) the country's fleet of vehicles tends to have smaller engines (few have more than 4 cylinders), they tend to have more turbo diesel passenger cars and many very small gas engines < 1.0 liter - 850cc passenger car engines are common. This says to me that when it comes to economising smaller = less expensive.
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"It takes more crude to produce one gallon of diesel than it does one gallon of gas."
Ann, if this is true, why is diesel the preferred fuel around the world? It seems that diesel is generally easier to find produce. Or am I totally wrong?
Dave
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In looking a bit further it seems that Ann is correct. But you don't get less diesel volume from crude at the expense of gasoline. The diesel and kerosene remain after the gasoline is refined.
The important thing is that diesel gives more energy at reduced cost.
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yes diesel kerosene and fuel oil are made from "waste" after gasoline is made. The process cost a little more which is why diesel costs more. Say you take one gallon of crude and refine it you will end up with about 1/2 gallon of gas. Then with the additives you still end up with about 2/3 gallon of waste which is then turned in to whatever. In the oil industry nothing is wasted.
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Ann is right. The most efficient would be a hybrid diesel. There are, however, quite a few of them around. Diesel-Electric locomotives and marine applications (cruise ships) to name a couple. Imagine how much fuel a train would use with a gasoline motor or heavy highway truck for that matter.
Just because its only used on "super-sized" equipment doesn't mean it's wrong for a family car/SUV. IMHO it just proves that it would make more sense in a smaller vehicle. A step beyond the gasoline-electric hybrid. Now if the gov can only get going with the low sulfer diesel and EPA allow the manufacturers to market some technology...
I for one hope that Dodge pursues the Cummins(diesel)-Electric hybrid truck. By the time it hits the market, I will be looking to replace my '94 Dodge-Cummins.
Just my warped opinion.
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To say that diesel is left over from refining gasoline isn't exactly what happens. Diesel and other long hydrocarbons are removed from the distillation process at a lower temperature than korosene and gasoline. Diesel has a longer hydrocarbon chain and thus a higher boiling point. It condenses lower in the tower and is removed. Diesel and other heavy oils can then be further "cracked" in a cracking tower and have their hydrocarbon chains furhter reduced to produce gasoline or other shorter chain by-products.
I'm pretty sure Golden Goebel was left over after brewing Strohs, and Red White and Blue was the residue of brewing Pabst Blue Ribbon, but diesel isn't really residue from refining crude oil to gasoline.
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Gas Generator Weather Protecti
08-25-2004, 12:23 
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