I understand it. I'm not sure most of the people posting know what they are talking about. They are pulling snips and quotes from papers and reports that are take out of context and support only the narrow point that they are trying to make. I can argue anything if you let me box in the statements with clauses and assumptions that don't have to be proven. Decide on a fair standard and then use the standard to evaluate both products. The fight will be about what is "fair."

-Enjoy.

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.

Jadavis, I think your statements are completely uncalled for. This has been mostly a civilized thread, so I don't know what you're talking about.

Craig, by energy efficiency I mean (energy output) / (non-renewable energy input).

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I absolutely agree that it has been a civilized thread. You are, however, argueing for the fun of it. Read back through the thread. I have.

I'm not here to Troll, so I'm going to take my notifications off of the thread.

Sorry for interrupting. I should have just shook my head and walked away after finishing the thread the first time. I would have kept all of us from wasting our time.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.

Not only has this thread been civilized but it's been informative as well. Would you care to enlighten us as to where we have erred or would you like to contribute something meaningful? If you have no interest in this thread, why even open it and read it?

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

thank you for the apology.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

so coming back on the subjet:

how can you get 300% efficiency if you define efficiency= energy output/energy input

That my friend is against all laws of physics

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Aquilae non capunt muscas! (Eagles don't hunt flies!)


1979 300SD Black/Black MBtex239000mi
1983 300TD euro-NA. White/Olive Cloth-MBtex 201000mi. Fleet car of the USA embassy in Morocco
1983 240D Labrador Blue/Blue MBtex 161000mi

Big trucks do it and get incredible mileage. 5-7MPG @80KLBS @70-90MPH is nothing to scoff at. Wouldn't a 8 or 10 speed gearbox in a passenger car serve about the same purpose as hooking up a generator and an electric motor? That way you could have a seriously wimpy motor and still push the car around efficiently. My major complaint with little diesel cars is the lack of gears... I would LOVE to have like 8 or 10 in a TDI or the Benz. Lots of shifting, but you would get used to it... kind of fun too. Am I completely wrong about this?

He was mixing definitions of efficiency. The 300% biodiesel is in reference to the energy return. To grow soybeans, press the oil, make biodiesel from the oil and burn it yields 3 times the energy used in the process; obviously the energy gain comes from the sun. This has absolutely nothing to do with vehicle efficiency in converting chemical energy to mechanical motion.

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'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg

truck drivers are professionals, the average car driver does NOT want 10 gears to shift through. improvements in CVT technology can accomplish the same goal. also, the weight of the extra gears on a truck is insignificant compared to the weight of the trailer, whereas for a passenger car the added weight would hurt economy.

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1992 300D 2.5T 249k - Parked with a bad transmission
1981 300SD 142k - Daily driver

Cars don't need 10 speeds. They could get along fine with a 3-speed.

MB's 7-speed is plain overkill. It's the same gearing as their 5-speed with two gears between them to keep the RPM's closer together. A CVT would do a better job, if it could handle the torque.

Semi's need 10+ speeds because they are moving 80,000lbs with an engine that has a 2500rpm redline. Our "little" GMC TopKicks *barely* get going with 6-speeds (moving 30,000lbs) and a 190HP 3126 Cat engine.

With the recent trend in rising fuel prices (although it doesnt seem like it right now.. it being election season and all), I think the "average driver" would be happy to learn how to depress the clutch a few more times pulling out from a stop light if it meant better fuel economy... also, am I totally wrong in thinking that the average driver's average car could have a much smaller than average motor that would still push it decently well if it had a slightly "larger" than average gearbox? It would defenitely be a different feel, but not necessarily any less driveable... I can't imagine a few extra gears would really weigh all that much... I'm not talking about putting a truck tranny in a car, more like a car tranny with more gears. What is CVT technology? It sounds expensive.

What I see to be overkill about MB's 7 speed is the size of the engine in front of it. What about a close-geared tranny with lots of gears with a tiny engine? Same principle as a truck with a small amount of power relative to the weight.

Trucks actually have an amazing amount of power. At Rock Mountain Truck Fest, I saw some stock semi's doing sub-21 second 1/4 mile times. Not bad for 13,000lb truck compared to my 300TD that did a 21.1 1/4 mile.

It's the limited RPM's that make semi's need so many gears. If they could revv to 5000rpm, they would very likely only need a 5 speed to get 80K moving.

Did you miss the part that says "non-renewable"?

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I bet your 300TD would do way better than that if it only weighed 16.25% of what it weighs now (ratio 13000:80000) My point is that the rev limit is NOT the reason semis have so many gears, it is that diesel engines of all varieties have a power band about 2 or 300rpms wide that when you are really pushing it, such as pulling a heavy trailer or pushing a car with a small engine, you have to keep the revs in. Example: Frito-Lay delivery trucks have a Cummins 4BT that tops out at about 2600rpm and a 4 speed transmission. So what. Well, the reason this works is that the engine doesn't *have* to be right in the power band the whole time, because the engine is oversize for the truck. If the truck had more gears it would be able to have a much smaller engine and be more efficient... no?