wishing for a hybrid ML

RE: Diesel...

The big economy advantage of a hybrid is in stop and go city driving, which is what most of us do most of the time. Quoting highway mileage misses the whole point of having a hybrid.

Hybrids also offer the advantage of very little wearing of the brakes as most of the braking is regenerative.

There is one adavantage for diesels : they make so much noise that you never have to use the horn....

DelJ

Wolfgang - 3/25/2005 10:36 AM

And diesel fuel economy is better: The E320 CDI gets 38 MPG on the highway, the RX400h only 26 MPG.

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RE: Diesel...

I am not mistaken! Hybrids work by recapturing the kinetic energy of the vehicle during much of the braking and stores this energy for subsequent propulsion. It is not necessary for the brake pads to be touching the rotors during regenerative braking, in fact this would undermine the advantage of a hybrid vehicle.

In actual use there will be a combination of mostly regenerative and some conventional braking. I wouldn't be surprised if the brake pads lasted over 100,000 miles and the rotors the life of the vehicle.

DelJ

Drew - 3/25/2005 9:22 PM
I believe you are a bit mistaken here. The brakes wear down the same as a regular car, however the car utilises the potential energy from slowing down to build up the battery life.

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RE: Diesel...

The General Motors 'hybrid' system is a very limited (lame) attempt on their part. Their own predictions on the upcoming GM hybrid products show very modest improvements, similar to what was achieved by the Seattle buses. I suspect that some marketing hype got out of hand in the Seattle case. The Toyota and Ford systems are much more effective.

You can read about how limited the GM hybrids are in this article:

http://www.canadiandriver.com/articles/pw/05gmhybrid.htm

Don't expect GM to ever lead the way.

DelJ

Wolfgang - 3/25/2005 6:44 PM

DelJ, just came across this article evaluating the hybrid bus program which may be of interest. They are mainly used in city stop and go.

http://www.energybulletin.net/3789.html

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RE: Regenerative braking...

Au contraire! Regenerative braking motors can apply as much reverse torque as when the motors are used for propulsion. It is just a matter of how much current can be fed into the batteries. The maximum charging current is currently a bottleneck in the Prius, but this can easily be overcome by using either bigger batteries or large capacitors.

Since kinetic energy is proportional to velocity squared, regenerative charging current limitation equates to very light braking at high speeds and but allows for much heavier braking at low speeds. Thus, as stated previously, hybrids offer the most improvement in stop and go city driving.

DelJ

Drew - 3/26/2005 9:10 AM

(snip) ..regenerative braking (snip) does not slow down the vehicle that much at all.

The brakes still do need to be used as usual as the motor/generator does not provide <i>that</i> much resistance.[/QUOT
E]

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I disagree. I am unaware of any significant issues having to do with hybrid driveability or reliability. Hybrids are on the road today from several manufacturers and seem to be working just fine.

The fuel savings are typically grossly underestimated as people tend to compare highway mileage when they should be comparing city mileage. Hybrids easily come out way ahead in crowded day to day commuting traffic.

It is the new advanced diesels that are unproven and full of hype. The last generation of diesels were a bunch of losers, and only the dieselheads were sorry to see them fall out of favor here in the USA.

DelJ

Tim - 3/26/2005 10:24 AM

Hybrids are still a science experiment waiting to be proven and in regards to economy, the extra cost is not made up in fuel savings until you drive 100K or more.

I'd much rather have an advanced diesel, expecially in something such as an ML.

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Diesel sales in Europe are artificially pushed by significant government tax incentives. Here in the USA diesel cost the same as gas and there are no difference in vehicle fees between gas and diesel variants, and so we Americans choose gas or diesel based soley on their respective merits. In this fair situation, diesel does not fare very well. I have driven the Mercedes diesels of the 1980's and they were truly awful cars and did not last as long as hyped. Just look for the phrase 'rebuilt engine' in advertisements for used turbodiesels.

The question you should ask is why do are half the European sedan sales remaining with gas engines when diesel costs so much less for them?

DelJ

Wolfgang - 3/27/2005 12:46 PM

DelJ - 3/27/2005 8:20 AM
It is the new advanced diesels that are unproven and full of hype.

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DelJ, I disagree and so do many others. Here's the percentage of diesels sold in a market where Mercedes offers both gas and diesel versions.

diesel market share
=================
Sprinter 100%
Vito V-class 97%
M-class 88%
G-class 67%
E-class 58%
Vaneo van 56%
C-class 55%
A-class 47%
S-class 40%
smart 35%
CLK 0%
SLK 0%
SL 0%

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I completely agree that diesel engines offer more economy. My objections were to the slowness, noise, vibration and smoke. Even the improved E300D of 1990's was still slow and clatters loudly after a few years. The latest diesel engines may or may not fix all this, but the past for diesels has been nothing to crow about.

My other big gripe is with all the nonsense one hears from the diesel crowd, such as less maintenance just because a gas engine requires new spark plugs every 100,000 miles. They seem to forget that diesel engines require more frequent oil changes. You can count even more maintenance for the new hi-tech diesels engines.

Finally, I would like hear just once from someone who is honest enough to simply admit that they bought a diesel to save money. I don't need to hear about locomotive transmissions or how hybrid cars were really invented 100 years ago.

DelJ

Andrew - 3/31/2005 12:07 PM

DelJ, Your evaluation of a diesel engine is falling a little short, today no other engine in practical use offers higher conversion of fuel energy into mechanical energy than a Diesel engine and further more there is ample room for continual improvement in the conversion rate.

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