How good mileage could the Prius get

^^^

Sorry, I was a bit off in my statement, but you get it.



<div class='quotetop'>QUOTE(Per @ Jun 9 2007, 06:47 PM) [snapback]458935[/snapback]</div>

 

<div class='quotetop'>QUOTE(Per @ Jun 13 2007, 08:18 PM) [snapback]461201[/snapback]</div>

Seems like you are missing the point that others are making. People are referring to weight since you have been comparing it to the mileage of the CRX. I don't think you have ever said where you got the 70mpg at 70mph number that you think the Prius should get. No four dour car with the standard safety/emission features gets 60 mpg at 70mph, with the current technology. That is what people are trying to say. Of course engine efficiency and technology can be used to raise mileage (like the Honda Odyssey's VCM), which the Prius does with the Atkinson cycle and smaller ICE.

Diesels hybrids haven't been made in passenger cars yet, suggesting that perhaps there needs to be technological improvements/hurdles to overcomes. So not to say that the Prius won't be a diesel hybrid in the future, but that isn't an option now. A bigger, heavier battery in the Prius isn't going to get a person 20mpg more on the highway, since the ICE is the primary source of power on the highway anyway (with your constant speed/level ground highway example).

It sounds like what you should have made is a thread to toss around ideas on how to make future Pri more fuel efficient. Then you would get more of what you are wanting in seems, a discussion of how future improvements/optimizations on the Prius could raise economy. There is a cost/benefit ratio too though where the more technological advances the higher the cost (in the short term at least). Carbon fiber seems like a good example, since it would significant optimize the Prius for mileage, but significantly raise cost.

 

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 06:15 AM) [snapback]461475[/snapback]</div>

In the real world, people are not going to maintain constant speed. Aside from the hills, which FE is affected by the weight, there is also traffic to contend with. Cars may have to slow down and speed up, or pass, or many of the other wonderful things that happen on a typical drive. Speed changes will be affected by weight. I don't think your ideal conditions would come up much, if at all.

 

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 06:15 AM) [snapback]461475[/snapback]</div>

um.... OK. I bet you have a hard time finding hats that fit. :lol:

 

Dymaxion sums up the Prius - fusiform (slippery through a fluid), with much thought into every component.

 

<div class='quotetop'>QUOTE(Per @ Jun 13 2007, 09:22 AM) [snapback]460910[/snapback]</div>

Not at all. The response has been that the Prius is the best today's consumer market will accept, given the costs and the compromises involved. Toyota judged (correctly, in my opinion) that today's consumers would not accept a car that had an additional $5,000 in batteries, or a smaller engine that took 15 seconds to get from 0 to 60.

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 06:15 AM) [snapback]461475[/snapback]</div>

See my comment above. Yes, more batteries will improve performance, but at a dollar cost most consumers would reject.

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 06:15 AM) [snapback]461475[/snapback]</div>

A given??? My, my, you are awfully certain, considering that you have no figures or evidence. I think that that pollution restrictions reduce FE by a relatively small amount.

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 06:15 AM) [snapback]461475[/snapback]</div>

Now you are sounding like an egomaniac. You really think you are a better engineer than the ones working at Toyota?

Technology is constantly advancing, and for this reason, the 2009 Prius will be more efficient than the 2004. Are you saying you could have done in 2004 what they are doing for 2009? Or are you saying that if you had "a job" in Toyota's R&D department, you would have defied the business managers and made compromises that those gentlemen had vetoed as being unmarketable? It would have been easy enough to use a smaller engine and achieved phenomenal mileage in a car nobody would buy; or to leave off all pollution control and produce a car it would be illegal to sell in the CA, which is the largest segment of the U.S. car market. But Toyota's engineers had to build a car that they could sell, and that people would buy.

If you are merely saying that you disapprove of the particular compromises made, that's your right. But those decisions are made by management, not by R&D. And if you think you are a better engineer than the ones at Toyota, then I think you have a screw loose.

 

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 08:15 AM) [snapback]461475[/snapback]</div>

Back in the 80's you are right, emission control had a large effect on fuel economy but that is not the case anymore. New advances in technology such and direct injection and variable timing are improving emissions, performance, and fuel economy.

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 08:15 AM) [snapback]461475[/snapback]</div>

You can design an engine to run a one RPM were it is most efficient and this would improve fuel economy as well as reduce expense because the engine would be simpler. Technologies like variable timing are designed to give a broad spread of torque over a large RPM range. You could do this but then you would have a series hybrid like you have in diesel locomotives or GM's Volt. The problem is that Toyota is married to their HSD and have publicly stated it is superior to a series hybrid. After working for a Japanese company I can say from personal experience it would be VERY difficult if not impossible for Toyota to switch to a series hybrid after these statements.

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 08:15 AM) [snapback]461475[/snapback]</div>

The EV-1 was aerodynamic but not as aerodynamic as a production car from the 1930's. It is also about 10% worse that GM's Precept concept. The problem is that people want "normal" looking cars. The Prius is not all that radical in looks and very similar to the people movers like the A-class or Ford C-Max sold in Europe.

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 08:15 AM) [snapback]461475[/snapback]</div>

With a diesel engine the Prius should get a easy 25% to 30% bump in mileage. 20% of that is simply because diesel has 20% more energy than gasoline and the other 5% to 10% is due the the fact that diesels have higher compression and no throttle plate.

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 08:15 AM) [snapback]461475[/snapback]</div>

I don't doubt it but the bean-counters, stylist, marketing staff, production people and management staff wouldn't let you build it or sell it. I have not doubt that Toyota could do better but chooses not to. The obvious solution would be to replace the 1.5L engine with 0.6 to 0.8L engine. Yes, it would be slow, but it would get better mileage. They could make it car shorter, the grill smaller, use wheel skirts and underbodies to reduce aerodynamic drag. They could do lots of things but have decided that the current model is the best compromise to sell the most vehicle at the best profit.

 

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 06:18 PM) [snapback]461898[/snapback]</div>

The problem with the argument you started out making, in drawing comparison between the CRX and Prius is clearly that weight does play a part, significantly, in fuel efficiency because as you acknowledge, real world driving does in fact include no small amount of acceleration and deceleration for a range of reasons which will impact directly on how many miles the vehicle will travel for any specified amount of fuel. Even in your cruise control example, the car is really not traveling at constant speed, but is in fact accelerating and decelerating with every slight incline and to make constant adjustments for wind, drag, etc.

It therefore stands to reason that improvements in fuel efficiency could be gained if the Prius was made lighter, and that particularly in city driving, even a 20% reduction in weight would be expected to gain noticeable fuel efficiency benefit. It also stands to reason then that taking actions that would ADD weight would tend to have a counter productive impact, even if otherwise improving aerodynamics, energy delivery etc. Likewise, removing power-sapping devices such as mufflers and catalytic converters would bring fuel savings, but at considerable cost in terms of noise, if not pollution of other kinds, and since doing so would breach legal constraints, it's not a practical option for Toyota to follow.

It seems to me that if one were to ignore the practical constraints of cost, one could build a Prius with, for example, something like a carbon-fiber body and gain better mpg that way, but nowhere near enough to justify the extra cost to the consumer of buying the product. Given the Prius is already not a truly economic proposition in purchase until it has been operated for more years than the average car buyer would likely keep it, adding cost and gaining a few extra mpg would be counter productive from a marketing standpoint.

Where real gains can be envisaged is in the technologies being developed now. Diesel engines, for example. The diesels available while the R&D for the current Prius was underway were clearly not satisfactory or suitable - possibly though a combination of factors such as weight, cost, efficiency gains, lack of widespread US acceptance, lack of compatibility or easy integration with the rest of the HSD technology - but clearly having kick-started the mass-market drive for fuel efficiency, the Prius may gain in the future from diesel engine technology being developed now. Likewise with improved battery technologies and efficiency allowing lighter power cells with higher capacities. Additionally, while in the past a plug-in option would likely have been a risk in that in the public perception it would cause the Prius to be seen in the same light as electric cars with poor range and limited functionality, as fuel prices rise and hybrid technologies gain wider market recognition and acceptance, a plug-in feature would be more likely to be seen in the context of the HSD overall, and understood more widely to be a positive benefit rather than a sign of a poor or dysfunctional product.

On the whole, I'd agree with the majority here so far that have suggested the Prius is, in reality, about as good a set of compromises as it was possible for Toyota to build and market at the time, given the technologies available, cost constraints and public perceptions in the marketplace. That the mk1 Prius was replaced by the mk2 which was not only heavier and faster, but bigger and more fuel efficient shows that the technologies are in constant development, with every reason to expect they will continue to be so. The current model has now in a very real sense opened the eyes of the mass market to fuel-efficiency and turned the Prius from a niche product into a respected and accepted production car that stands in its own right. As such, I think that while it may be reasonable to suggest that, perhaps, Toyota COULD have made it more fuel efficient to some degree (using the existing HSD in a lightweight version of a mk1-type body for example) they actually did an incredibly good job finding the right set of compromises to bring a fine car to a market that really didn't previously exist, and then sell it to people who would previously have never given it a second thought or taken it seriously enough to throw their money at.

It's that feat which provides the foundation on which the next generation Prius can be built, and on which history will, I think, show the entire market for fuel efficient vehicle technologies will have sprung.

 

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 11:46 PM) [snapback]462127[/snapback]</div>

Undertrays do not change the look of the car but they add money for something the average person would never see and wouldn't understand the purpose for if they did. My Jetta TDI has an tray that fits under the engine compartment and one on top of the engine that are used for noise reduction. The undertray also helps with aerodynamics because it smooths out the airflow under the car. Most of the guys over at TDIclub that do their own maintenance throw the trays away at the first oil change because it takes 15 bolts to remove them and they didn't understand the purpose.

Sideskirts have never been popular or accepted since the 50's and if you make them removable so people can throw them away what's the point? Once again, more money for something people don't want and you may turn people away who see the car with them on TV or at the dealer.

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 11:46 PM) [snapback]462127[/snapback]</div>

That's an easy one to figure out. Look at my signature, I have a VW TDI diesel that gets the same mileage as the Prius. When my wife was using it to go back and forth to school and all the mileage was state 4-lane highway driving we were averaging 49 to 50 mpg. It get 52 to 55 mpg on the highway at 70 mph to 80 mph with the cruise set. For the past 3 years my job had me traveling 60 days a year in Europe so I spent a lot of time driving some of their very nice diesel cars that are not available here in the U.S. I like diesels but still think the future is electric and hybrid drives, just not Toyota's HSD. I think the future will be a mix of pure EV's and series hybrids with very small 0.5L to 1.0L generators.

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 11:46 PM) [snapback]462127[/snapback]</div>

Engineers do not run companies, business, sales, and marketing people do. Having worked in the R&D department of a Japanese company as recently as 2 weeks ago, I would have to disagree with you. There are lots of talented folks and brilliant new ideas, but most of these get passed on for steady evolution of the current product. It has worked well for them in the past but may not work so well in the future. You also have the issue of promotion based on seniority and family instead of talent. It leads to stagnation and continued one-track company think. They do have an advantage in sheer hours worked. I good friend of mine just got back from a 3 month training rotation to the main factory is Osaka, Japan and their normal work day is 10 to 12 hours with a 30 minute lunch break. Since he was training and not from the plant he didn't have to work on Saturdays because they wanted him to get a chance to site-see do tourist stuff but most of the engineering staff works a 6 to 8 hour day on Saturday too. So a 55 to 70 hour work week is normal for a Japanese engineer at least in the company that I worked for.

 

<div class='quotetop'>QUOTE(Per @ Jun 14 2007, 09:46 PM) [snapback]462127[/snapback]</div>

It is no secret that low emissions was the primary goal, and better FE was a secondary goal. And that's why I bought the car, along with the technological gadgetry.

Note that a one- or two-mpg improvement in FE makes a very small difference in total fuel consumption, whereas raising cars from ULEV to SULEV, across the entire fleet, would make an enormous difference to urban air quality.

Note also that there's no point in building a car nobody would buy, so that the R&D people have to keep performance up and cost down as they improve FE.

I'm glad to see you are finally agreeing with me, that the 2009 Prius will do the things you've been asking for. In 2004 Toyota produced the best FE and lowest emissions that 2004 technology was capable of, consistent with the demands of the market and the PRIMARY goal of reduced emissions. In 2009 Toyota will produce the best that 2009 technology is capable of. And they will continue along the same trajectory, until the rate of increase in the price of gas exceeds the rate of progress of technology, and then they'll have to abandon fossil-fuels entirely and either switch to electric or go bankrupt like GM.

Enjoy the stink of gasoline while you can, because pretty soon you won't be able to afford it any more.

 

This thread has evolved into a very nice discussion of the pros and cons of the Prius design. Just wanted to throw a few things out there.

1. Did anyone get my Hat joke?
2. I dont think Diesels will ever work for Toyota's Hybrid design because of the high internal friction of a diesel. It is not the compression ratio that causes the friction, it is the friction from the extra piston rings, etc. Toyotas hybrid system often requires the ICE to spin without providing any power.
3. There is so much missconception regarding the Prius. First question my carpool partner asked me was "how long until you have to replace the battery?" Obiously a leading question. My wife asked if we need to plug it in.(she is actually pretty smart when it comes to cars, too).
4. Under belly pans are expensive, prone to damage and increase repair costs. Wheel skirts are ugly. (Honda Insight).

 

Safety

I have not seen anyone touch on this topic. The safety standard required by the federal government is not the same as 20 years ago. Today's car will be heavier due to this fact. I am curious to see the crash video between Prius and that Civic.