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bwilson4web
User Rank
Gold
Re: The number is actually a compromise
bwilson4web   8/27/2012 5:14:28 PM
NO RATINGS
You mentioned, ". . . the TDI with a manual transmission will get between 42-57mpg in a Beetle and Jetta ...the automatic is significantly worse ... that is personal esperience across a number of drivers."

This is why looking a populations of drivers is more important than what any one vehicle or driver accomplished. Wayne Gertes goes out of his way to set MPG records in any car he gets a chance to drive. But these are anetodota cases that do not show up in populations of drivers. That is why each time you'll find I'm bringing a collection of driving records, not ones-twoies.

You also claimed,". . . the serial hybrid in the Prius is horribly inefficent . . ." while ignoring the parallel path. Engine power flows through a power-split device where 28% takes an electrical path, ~82% efficient, and 72% takes a single-stage, mechanical path, ~98% efficient. If you remember how to do partial fractions: (28%*82%) + (72%*98%) ~= 93% engine-to-reduction gear efficiency. It makes up for any losses in this path by keeping the engine in the peak efficiency region during normal highway cruise. Thus the "GreenHuman" Portland-to-Portland stunt found the fullsize Prius came within 1 MPG of the compact Jetta TDI in spite of trying to shag the 'test' by just Interstate driving in the winter.

As you pointed out," . . . price of diesel varies over time" but since the mandate for low sulfur diesel, it has run consistently higher than regular gas. We have to pay today's prices, not yesterday's memory that can often leave out the ugly details of soot-laden exhuasts.

A great believer in the right tool for the right job, I was pleased to see,"both gas and diesel GM Suburbans and Pickups." Toyota has finally gotten a clue and today's Prius includes four models:
  • 1.5L commuter model
  • 1.8L standard hatchback (what we have)
  • 1.8L station wagon
  • 1.8L plug-in

What is missing from the hybrid offerings are: small pickup (aka., S-10, Ranger sized) and utility van (aka., Ford Transit sized.) These would provide a solid family of fuel efficient hybrids to meet pretty much the remaining market. Then we could do with some 'super-sized' versions using the 2.4L Camry drivetrain.

I don't really mind if someone else finds happiness with an inefficient or oversized vehicle as long as I can get mine. As they burn up the remaining gas supplies, the fuel efficient vehicles become more and more attractives and take more market share. One thing for sure, they ain't making more fossile fuels as fast as we can burn 'em up.

Bob Wilson, Huntsville, AL

William K.
User Rank
Platinum
Re: 54.5 MPG at WHAT cost?
William K.   8/27/2012 5:12:22 PM
NO RATINGS
I would love for some very good engineers to solve the problems that I have described, I really would be very happy to be shown to be incorrect on those assertions.

But I just don't think that it will happen.

It has been shown repeatedly that it is very difficult to make people like something, and it has been demonstrated many times that consumers will resist purchasing something that they don't like and don't want.

analyst
User Rank
Iron
Re: Lame skeptics need to be taught a lesson... again
analyst   8/27/2012 5:06:07 PM
NO RATINGS
@Totally Lost

60% is a better figure for combined cycle natural gas electric production, although according to www.naturalgas.org, natural gas powered microturbines using new waste heat recovery techniques can achieve energy efficiencies of up to 80 percent.

Totally_Lost
User Rank
Silver
Re: Lame skeptics need to be taught a lesson... again
Totally_Lost   8/27/2012 4:54:30 PM
NO RATINGS

Right: You have to add up all the losses. Including the 80+% efficiency of the steam turbines making the electricity and the efficiency of the high voltage transmission lines.

Wrong: The net efficiency of a EV is three times that of the pitifully inefficient gasoline powered engine when you add up all THEIR LOSSES, including the ever increasing energy cost of extracting crude out of the ground, transporting the crude and finished gasoline, THE ENERGY COST OF THE CRACKING PROCESS that converts crude into something useful in a car.

And all those additional costs apply to digging up coal that burns with radioactive stack waste, 7% transmission losses, further reducing the efficency of plug in EV's

I don't know where you get 80+% efficency from. Heat recovery gas steam turbines typically are below 60%, and coal fired plants below 30%.

 

Chuck_IAG
User Rank
Platinum
Re: From the 2% hybrid market
Chuck_IAG   8/27/2012 4:45:00 PM
NO RATINGS
You actually do a great job of highlighting how owning a Prius is a status symbol in and of itself.  You automatically attain tree-hugger status even if you keep the thermostat in your house set at 60 degrees all summer and you drive two blocks to the local grocery story for a loaf of bread.

Did I mention the smugness aspect?  Oh wait- I see that you touched on that already.  Good job.

analyst
User Rank
Iron
Re: 54.5 MPG at WHAT cost?
analyst   8/27/2012 4:42:56 PM
@William K

The good engineers love people like you. They love proving how wrong you are by SOLVING THE PROBLEM.

 

jbswindle
User Rank
Silver
Owner's report
jbswindle   8/27/2012 4:41:59 PM
I've bought two new cars in the past 8 years: a 2004 Prius and a 2010 Prius, both first years for new models.  The 2004 now has about 193,000 miles and and 2010 has about 68,000 miles from a mixture of distant travel (3000 miles/trip) and metro driving (Dallas/Ft Worth metroplex).  The two cars replaced respectively a 2002 Civic and a 2002 Accord.  The Civic got about 36 MPG and the Accord got about 26 MPG.  The 2004 Prius gets about 45 MPG and, since tire replacement (with the OEM tires we got consistently 50 MPG), the 2010 gets about the same.  Over the lifes of the Prii the 2004 has consumed about 4300 gallons and the 2010 about 1500 gallons.  Had we kept the Hondas comparable fuel consumption would have been about 5400 gallons and about 2600 gallons, respectively.  That scores about 1100 gallons for the 2004 and about 1100 gallons for the 2010 that we didn't consume, hardly justification for the two cars' purchases.  The numbers are considerably different, however, if you substitute US national average milage of 20 MPG for the Hondas milage.  Then the fuel saving looks like about 7200 gallons. Taking an average fuel price of $2.50/gallon the savings in dollars is more than $15,000.  But that's not all.  The Prii require almost no maintenance.  Spark plugs last 140,000 miles, for example.  I've never owned a more reliable automobile nor one that required less routine maintenance than a Prius.  The one machanical failure I have experienced was a water pump (there are 4) on the 2004 and that was covered by the vehicle warranty.  Bottom line: I'm satisfied.

analyst
User Rank
Iron
Re: We went to the moon, 54 MPG both easier and safer
analyst   8/27/2012 4:39:06 PM
@Totally Lost

All I can say is that you said nothing in your last.

Meanwhile, the do-gooders have saved your life, or someone close to you. They made the US must less susceptable to oil price shocks. And they are responsible for us not having permanently contaminating our drinking water.

I tremendously admire the do-gooders, like the ones currently trying to rid the world of malaria. But then there are the nattering nabobs, like you.

I am sure you serve some purpose here on Earth.

Perhaps as a bad example.

Chuck_IAG
User Rank
Platinum
Re: CAFE loop holes
Chuck_IAG   8/27/2012 4:37:31 PM
NO RATINGS
MPG-e, mile per gallon equivalent.  It's factored into Nisan Leaf efficiency- an all-electric vehicle uses no gasoline but for mileage-comparison purposes you calculate the energy a gallon of gasoline provides and compare that to the amount of energy that the electric car typically consumes, and then compare ranges.  Like a gallon of gas produces about 114k BTUs of energy, which translates roughly to 33.41 killowatt-hours of electricity.  So a gas-driven car that consumes a gallon in 20 miles of driving is the same as an electric car that uses 33.41 kWh of electricity for that same distance.  Chart on it here if my explanation is muddy:  http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent

All of those equivalents are politically charged, though.  A gallon of gas uses energy to refine it.  33.4kWh of electricity also have production costs.  How do they compare? etc.

William K.
User Rank
Platinum
54.5 MPG at WHAT cost?
William K.   8/27/2012 4:31:47 PM
NO RATINGS
The problem that will arise when they make the car that gets that kind of mileage is that nobody will want to drive it, completely aside from the fact that it will cost too much.

For starters, current vehicle safety rules demand that hitting a solid barrier at 45 MPH with an unbelted driver produce no injuries. That can't happen in a 1500 pound car, no matter what it is made out of.  So some sort of compromise will be required as far as crash survival will need to happen, which is a lot less likely than a magic 120MPG carburetor being invented soon.

But the biggest problem is that folks just don't want to drive a car that small, and any attempt to force people to drive cars like that will result in open insurection, since it would require either a huge tax increase or a huge decrease in personal freedoms. If folks did want to drive those tiny cars, they would already be driving them because the car companies would already be selling them. The car companies are not stupid! At least not so stupid as to ignore a real market such as that.

One option that is being totally ignored is the start-coast-stop system, which could reduce vehicle fuel usage as well as polution in most city driving. Not computerized start-stop, but under driver control. It does require both driver skill and attention, but it does work very well. And the very best part of this concept is that evebry piece of the hardware needed has already been put into vehicles presently in production. So the entire design effort would be in integration of the parts and creation of the driver interface, neither of which should be that hard. 

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