If the traction battery has the charged potential to move the car 1000 ft it doesn't matter if it's at acceleration from a dead stop or dispersed for the next couple of miles. So, I agree with your experience 100%. I disagree with your one week assessment of mpg though, unless you filled the tank several times during that week.
BTW, I'll be at Thorn's market today sometime around 1 pm. I'm easy to spot. I won't be wearing a winter coat ;)
You are right about the way locomotives operate and why they are diesel-electric (as are many truly huge machines). But you are mistaken to call them hybrids - they have only one power source, the diesel engine. They just have electric transmissions.
Hybrids today get their main efficiency improvement from not using the engine as much to do ludicrously inefficient work. As the OP noted, the engine is still used at times that don't make a lot of sense. Blame that on the infancy of the technology.
Actually, it is an engineering solution to a fundamental conceptual problem. Even as a teenager learning about cars I was struck by the horrible inefficiencies of using large engines to put out negligible power for nearly the entire range of the car's operation. But it was the '60s and gas was cheap. When I first heard about hybrid power trains (around 20 years ago) I immediately recognized them as the solution to the century-old problem.
Ah - that's where you are 100% wrong. One of the central characteristics of hybridization is that the acceleration performance is independent of the power plant capacity, just as a conventional power train's performance is independent of fuel tank size. The engine can be off or just plain dead without affecting the immediate performance of a serial hybrid (none in production yet, sadly). A serial hybrid is essentially an electric car with a charging system on-board. Right now the technology exists to build a serial hybrid that will give the hottest conventional power trains a run for their money; a Tesla
I think you misunderstand the statement. If the meaning was "the car reuses only part of the energy that was regenerated" that matches my experience and even the logic - there is considerable loss and waste in the process. Toyota says "up to 30%" of regenerated energy is reusable, so the process is pretty lossy. But it isn't nearly as inefficient as getting the energy out of an engine running at 10% power, so it still contributes to the overall gain. There is a widespread misconception that regeneration is a major source of the hybrid's efficiency advantage. In actuality, it is a very minor contributor.
Mike
Okay if you don't want to call a diesel-electric locomotive a hybrid, that's fine with me. But you shouldn't call hybrid cars hybrids either. They get all of their energy from their IC engine also. The only difference is that hybrid cars also have a mechanical drive train along with their electrical one.
No, it uses the IC engine more. The IC engine powers the car at all times, even when it isn't running. If the IC engine isn't running, the car is using energy produced by the IC engine at some time in the past and stored in the batteries.
You're confusing acceleration performance with efficiency.
Mike, you can't ignore physics. It takes energy to accelerate mass. Increase the mass and you have to increase the energy input to maintain the same performance level. That's why all economy cars are small and light. More mass also equals higher rolling resistance which requires energy to overcome.
You can use a battery and electric motor to increase the acceleration performance of a car with a small IC engine but you will have to put back the energy you have used at sometime in the future. Each time you convert from one form of energy to another, you will have losses which can't be overcome. You start out with the chemical energy contained in a gallon of gas. Then you burn that gas to produce heat energy but you can't capture all of the heat. You convert that heat energy into mechanical energy with an IC engine which has internal friction losses. Both hybrids and conventional cars have these same losses. To this, a hybrid car adds changing that mechanical energy into electrical energy using an alternator, friction losses and heat losses. You use that electrical energy to recharge a battery converting electrical energy back into chemical energy with it's associated losses. Then, at some time in the future, you discharge that battery converting its chemical energy back into electrical energy with more losses and that electrical energy back into mechanical energy with even more losses.
There ain't no such thing as a free lunch. Perpitual motion is a thing of fiction. If you believe all of these conversion losses add up to an increase in efficiency then you might want to buy this ethanol plant I have for sale.
Don't get me wrong, I like ethanol. When its aged in charred oak barrels for 10 years or so and then mixed with a little water. But burn it for fuel....man, that's just plain wrong.
I guess every manufacturer does it differently. Honda cruise control will remember the speed until you shut off the engine or at least the CC master switch. However, the CC cannot be engaged at speeds below ~20 mph. I think they want to prevent someone from inadvertently engaging the CC and having the car jump from a stationary position.
The Prius can run for a very short time on battery only, but the battery pack isn't large enough to run the car very long or very fast on battery power alone.
How is improving fuel efficiency a political problem?
Your theoretical argument about efficiencies reminds me of creationists who want to make statistical arguments to claim evolution couldn't happen. Dude, the proof is right before your face. Hybrids get much better mileage than a similar/identical car with similar performance with only an ICE.
But you are neglecting the factors which make hybrids more efficient:
The electrical system provides a means of recovering kinetic energy during braking. The energy which would have gone into heating the brake rotors (and wearing out the pads) is converted to energy stored in the battery. Virtually all of the battery charge comes from this source. Even 50% efficiency in recovery of energy which would have been wasted is efficient.
The availability of energy stored in the battery means that the engine doesn't have to provide all the energy under conditions of maximum demand. This allows the engine power to be down rated and therefore run at more efficient (higher) power levels more of the time, e.g. cruising.
The availability of electric drive allows the engine to be shut down at times when it is least efficient, e.g. idle and low speed operation.
But don't try to factor all this together, just look at it as a black box. You put gas in and go farther and/or faster than in a comparable non-hybrid car. What more evidence do you want?
If it is in Scotland and they are aging it for at least 12 years, let me know.
You act like hybrids are hydrogen fuel cells. People are driving hybrids now and getting far better mileage than with conventional cars. It is a proven, practical technology. Using your reasoning, a Prius should be getting 16mpg and no one would be selling them, let alone buying them.
But they make it with corn. If they were making it with barley, you would have a point. ;-]
Yes, and you've already said that that was on a pre-production model in 2000. The car has had numerous changes since then! I suggest that you try another week test drive in a current NHW20 Prius.
(There's also far better emissions controls (notorious for lowering fuel economy) since your AT Tercel... and I won't get into the apples and oranges of comparing a manual to an automatic CVT...)
2004-2007 UK tire Bridgestone Turanza ER30 195/55R16 87V
(Note the different size than the US!)
UK and Canada uses MPG using imperial gallons. Canada and most everywhere else use l/100km. Japan still uses km/l.
Most anti-hybrid kooks are narrowband thinkers. They don't like to see the world as a web of influences. A simple straight line is about as complex as they can handle. For example, your point about the regeneration system sparing the vehicle's brakes ought to suggest to them another indirect saving: less wear on brakes; longer intervals between replacements; less use of materials and energy in their manufacture/replacement; and lower bills. Yet I live in hope that it'll click for them, one day.
You can view the NHW20 Prius battery charge levels at:
(Also, if the hybrid battery cannot accept any more charge, it simply will not. You will no longer have regenerative braking, and will be switched to a higher percentage of conventional hydrolic braking.)
If you are just driving around in the green and don't notice anything else different, then you aren't regenerating more than you can use...
The engine isn't subjected to the strains of differing torque. The motor handles that load quite nicely. Extra fuel usually needed (remember the accelerator pump?) when lightly stepping up the speed is nicely handled by the motor instead.
If someone wanted to get off the starting line as fast as I can they better re-do their fuel economy calculations and stop lying through the teeth about that one-time 36 mpg fillup. Man! You might think us hybrid owners just fell off the alien turnip truck. mark_
What I am pointing out is that efficiency has increased along with performance - that is a basic characteristic of hybrid cars. Your premise was that it couldn't be done.
If all we were doing was accelerating mass, there wouldn't be an issue. The fallacy is that it takes some specific energy to accomplish the movement of mass from one place to another, even if the height of the two points is the same. That is not true at all; the efficiency of that operation is always zero since the final potential energy is the same as the initial potential energy. The question is how much energy is going to be wasted in the losses.
For the sake of argument we can keep the frictional losses the same, in which case the question is in the efficiency of the motive source. That is where conventional power trains are so dismal, running at a tiny fraction of their full power output and suffering the staggering losses that go with it. Hybrids make their biggest gains by using the power plant more efficiently. Not that much more efficiently at this stage, but doubling the efficiency from dismal to lousy is no big trick. There is something very wrong with using a power train that is less efficient at 30 mph than at 60 mph.
The proof is in the actual performance - even hybrids such as the Prius typically double the fuel economy of equivalent conventional cars in town. On the highway, where the air resistance losses are dominant, the advantage is much lower.
Mike
What are the major contributors, then?
I'd have to assume shutting down the engine at stoplights helps a lot for the EPA city mileage number.
Good aerodynamics and tires with low rolling resistance, certainly.
Thinking about it, regeneration might be minor, but not "very" minor. What else could cause the jump from 30 to 50 MPG?
Interesting advice -- I'll have to try this.
The B transmission setting is my favored way of doing this. I believe it saves the brake pads, and it does not bother my passengers.
That would go partway to explaining why a US Prius gets better mileage than a UK Prius. Although I can't find the exact size, Turanza have significantly higher rolling resistance than Goodyear Integrity tires. Also the 195 versus 185 width increases aerodynamic drag.
You know, these are topics that have been well talked through in the not-so-distant past. Google would be your friend.
But: petrol engine's efficiency (Atkinson Cycle IIRC: less power developed for same displacement as commonplace Otto Cycle engine yet much better use of fuel) and general engineering qualities.
The notorious electrical bits allow some of the others. A Prius doesn't break down easily into "this only does that". Parts are idiosyncratic for more than one reason, often as not.
Day-to-day: engine properly warmed; tyres at right pressure; how it is driven and maintained; type of fuel.
For the sake of the experimental data, I have just been outside to check my 2005 UK Prius: out in the dark dank chill with just my feeble torch for company, as winds moaned and owls hooted...
Bridgestone Turanza. Couldn't make out the associated numbers. But the tyres fit fine. :-)
I hope you lot appreciate that this effort was above and beyond the call of any duty. Where do I apply for my medals?
BTW, why don't they fit Integras in this market? Mine was made in *.jp, so they can't be any harder to find. Conflicting road demands and/or national car type certification conditions?
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