Highway Speed Hybrid and MPG Ranting

[chasd60]

I see all of the hybrids being manufactured today are best suited for city driving. The reasoning is because most of the fuel is used to get the mass rolling and they can accomplish that portion with an electric motor. I understand why they do this but some of us live in fairly rural areas and would benefit more from a hybrid that uses the electric motor as an assist at highway speeds.
 
I have heard that it only takes about 5HP to maintain 55MPH or so. I also know that is it hard to make an engine that has 300HP very efficient when only 5HP is required. I would think that a variation of the existing platform could be made for highway commuters. I travel 46 miles to work with all but 4 miles highway.
 
I see the Honda Insight is rated for 66MPG highway which is not very impressive given today's technology. I owned a 1993 Geo Metro XFi that was rated 53 city and 58 highway. The curb weight for the Metro and the Insight are about the same. The acceleration for the Metro and the Insight are about the same. The interior volume of the Metro is actually more than the Insight.
 
Doesn't it seem that the advancement in technology should be great enough to get better mileage than they presently do? I mean in 13 years they have taken the top rated MPG and only increased it by 8MPG. I would think just dropping the old Metro motor in an Insight would get better than they do now. The Insight is better aerodynamically and would weigh much less if you yanked the batteries and controls for the power generation. Imagine what you could do with the Suzuki motor that was in the Metro and just improved upon it with today's technology and dropped it into cleaned out Insight.
 
It seems to me that the car manufacturers are not as concerned with improving the fuel mileage as they are with chasing the technology that gets the highest subsidies. Look how fast electric cars died when the subsidies stopped.
 
OK, I'm done now.

[Jeffrey]

I owned a 1993 Geo Metro XFi that was rated 53 city and 58 highway.

Even simpler.......why isn't there a gas vehicle that gets the MPG they did in 1993? They don't offer anything close to that anymore.

And almost everytime they update vehicle models they increase HP decreasing MPG.

[fritz_monroe]

It seems to me that the car manufacturers are not as concerned with improving the fuel mileage as they are with chasing the technology that gets the highest subsidies. Look how fast electric cars died when the subsidies stopped.
 
OK, I'm done now.

Dead on here.  Take a look at the papers and you won't see a day go by that they are not talking about hybrids.  As long and this is hyped the way it is, the manufacturers will keep at the same thing.  It sells for a premium.  What incentive do they have to put out something that is improved beyond the current generation?  None.  If a company puts out a product that is way ahead of the competition, that product has to be priced so far above the price of anything else, that there isn't much of a market.  That company gets to claim bragging rights, but you can't take those to the bank.

[wavery]

I'm not sure where you got the 5hp @55mph info. I can assure you that is not correct. Every vehicle differs in wind resistance, gear ratios and road resistance but it takes 5hp just to run your A/C compressor and alternator.

You will notice that most late model vehicles run 55mph at a much lower RPM than they used to. This is done by automatic over-drives, gear ratios and a much lower vehicle weight. An engine that puts out 200hp does so at it's max rated RPM. This is usually about 5,000RPM. At 55mph, that engine is probably turning about 1000rpm + or - and putting out less than 50hp and that is what it takes to maintain that speed over a flat surface. HP increases dramatically as RPM increases. An engine at idle puts out less than 10HP. You will notice that if you climb a hill, the car will automatically gear down. That is to give it more RPM, thus more HP so that it can meet the demand of climbing the hill.

Trust me, the auto manufacturers have all this stuff down to a pretty close science now. A 350 Chevy V8 in a Monte Carlo got about 18MPG in '75 now gets about 28mpg and never needs a tune-up. I'd say that is one heck of an accomplishment.

The real answer is switching to all electric cars fueled by fuel cells that burn water. Electric motors run at their rated HP at every RPM. That make them much more efficient and eliminates the need for a transmission all together. Electric motors can be geared much lower than a gas engine because they are capable of turning up to 20,000RPM (some of them) and put out the same HP at 500RPM as they do at 20,000RPM. Therefore, they can get away with having a much lower HP rating. Remember, the example of the engine that is putting out less than 50HP at 55MPH. If you want a car that is only capable of doing 55MPH, you would only need 4 - 12HP electric motors to accomplish that job and it would accelerate much faster to that speed because it would have that HP from a dead stand still. If you want a vehicle that would tow a trailer at 70, you would just ad enough electical HP to do the job.

The fuel cell cars have one motor that drives each wheel, which gives you 4WD. At highway speeds, the motors can be disengaged when not needed.

The draw back on all of this electric car technology is electrical storage capacity. That is where technology has really fallen behind. We are still using the same battery technology that was developed over 100 years ago.

If you want to become the richest person alive, come up with a more efficient way to store electricity then todays batteries.

[Jeffrey]

Trust me, the auto manufacturers have all this stuff down to a pretty close science now. A 350 Chevy V8 in a Monte Carlo got about 18MPG in '75 now gets about 28mpg and never needs a tune-up. I'd say that is one heck of an accomplishment.

My '73 Monte never got over 12.

So why does the little Aveo get only a few lousy miles better than the Monte today? Their science is messed up somewhere.

[wavery]

My '73 Monte never got over 12.

So why does the little Aveo get only a few lousy miles better than the Monte today? Their science is messed up somewhere.

It all has to do with weight, HP, gear ratios, wind resistance and the efficiency of burning the fuel (in that order).

In the case of your Aveo, I'll bet that it gets a LOT better mileage at lower speeds. The Monte is built to handle higher speeds with a more powerful engine. The Aveo may be a lot lighter with a lot less HP therefore effecting the efficiency.

[zamboni]

I think the real reason, is lack of focus and incentives.  Some even hypothesize that the oil industry squashes research.

I, personally, am dismayed by the "progress" in fuel economy.

In 2002, VW unveiled their "1-liter-car".  A 2-seater (tandem) car that got 100 km/liter.  In a test run, it achieved 100 km in only 0.89 liters of gas.

264 MPG

http://greatchange.org/footnotes-1-liter-car.html

Unfortunately, in 2005, they abandoned it because they could not build it for under $25,000 (their target).

Nonetheless, the technology is there.

The VW Lupo (3-liter engine, $19K) gets 78.4 mpg.  TODAY.

Most cars in Europe get over 50 mpg.

[Jeffrey]

It all has to do with weight, HP, gear ratios, wind resistance and the efficiency of burning the fuel (in that order).

In the case of your Aveo, I'll bet that it gets a LOT better mileage at lower speeds. The Monte is built to handle higher speeds with a more powerful engine. The Aveo may be a lot lighter with a lot less HP therefore effecting the efficiency.

Sure but they did alot better in 1993. With chas's Metro, there is no  replacement for it now.

------------------

A Highway speed Hybrid, probably wouldn't run the gas engine enough to keep the battery charged. But I agree we don't all live in NYC or SF, The current Hybrids would be little good to me.

[wavery]

I think the real reason, is lack of focus and incentives.  Some even hypothesize that the oil industry squashes research.

I, personally, am dismayed by the "progress" in fuel economy.

In 2002, VW unveiled their "1-liter-car".  A 2-seater (tandem) car that got 100 km/liter.  In a test run, it achieved 100 km in only 0.89 liters of gas.

264 MPG

http://greatchange.org/footnotes-1-liter-car.html

Unfortunately, in 2005, they abandoned it because they could not build it for under $25,000 (their target).

Nonetheless, the technology is there.

The VW Lupo (3-liter engine, $19K) gets 78.4 mpg.  TODAY.

Most cars in Europe get over 50 mpg.

Same rule applies:
"It all has to do with weight, HP, gear ratios, wind resistance and the efficiency of burning the fuel (in that order)."

I don't know why you think that most Euro cars get 50PMG. We sell Mercedes, BMWs and all the other cars right here in the good old USA. I don't see them selling a lot of 50MPG cars here.....You know why............we want our big gas guzzling SUVs. You know how I know that....I look out on the street and that is what people are driving. If they wanted 50MPG Euro cars, they would buy them. The fact is, they don't.

The only place that I saw small cars in Europe was in Italy and Greece. That is because the streets are so narrow that they can't drive the big "tanks" down them. I'll bet that you wouldn't drive one of those things. Heck, you can buy a Mini here. One of my tenants has one of those things. I can't even get in it. It's tooo small. She told me that she gets about 35MPG in that thing. I get 28MPG in my Chrysler Concorde.

[Miller Tyme]

I have to chuckle every time I see that annoying Honda Hybrid commercial(the one where the couple talks, and the voice balloons have flowers in them):rolleyes: Honda claims the new Hybrid Civic gets close to 50 MPG.
 
 My next door neighbor bought a new Civic back in '75, with the 3 cylinder engine, and Honda claimed BACK THEN that the GAS Civic would get close to/slightly over 50 MPG.:eyecrazy:
 
 So now, I guess technology at Honda went back in a time warp to accomplish what they did 30 years ago....but at almost triple the list price....:yikes:

[zamboni]

I don't know why you think that most Euro cars get 50PMG.

True, I should have qualified that with "commuter" cars.  Sure, they are small - but so are Geo Metros.  The European version of the VW Golf gets in the upper 40's MPG.  The cars my friends in England buy, and that we saw in Paris (ie, city), were not large.  Since gas is so expensive, the average consumer buys cars with high economy - and they are not necessarily "small".

Shoot, the VW Golf TDI is available here, and gets 42/49 MPG (2002 version, though 2006 gets 43 highway)... and that is with a turbo.  The VW turbo diesel engine, on a highway, has proven more efficient than the Prius.  The same engine powers the larger VW Jetta with over 40 mpg.

[chasd60]

It appears that a small car would be about 17hp

Information presented below was taken from a webpage written by
 C Johnson, Physicist, Univ of Chicago
http://mb-soft.com/public/headlite.html
It is actually written about how much extra fuel it takes if you drive with your headlights on during the day but I only copied the information pertinent to this discussion


"First, we will consider the air resistance of a moving vehicle. A parameter called the dynamic pressure must be multiplied by the frontal area of the vehicle and by a factor called a shape coefficient (CD (or aerodynamic coefficient of drag) to get the actual total air-resistance force.  Streamlined vehicles have a lower CD, as low as 0.2, while more boxy vehicles have coefficients nearly 1.0.  These are all easily determined values. The result is a value (at 60 mph speed) of around 120 to 170 pounds of air resistance force, for a mid-sized sedan-style car.  Here are the values for one of my Corvettes, a fairly aerodynamic car. Dynamic pressure (only depends on speed and not the type of vehicle) at 60 mph is around 18.6 pounds per square foot.  (at 70 mph 25.3 psf). The frontal area (from GM) is 19.0 square feet, the aerodynamic coefficient of drag is 0.330.  The aerodynamic drag coefficient is relatively constant at different speeds.  So, for my car at 60 mph, the Aerodynamic drag is 19.0 * .330 * 18.6 or about 116.7 pounds.  (at 70 mph it is about 158.9 pounds, and at 40 mph, 51.9 pounds). The Tire Resistance drag is (at 60 mph) around 0.015 of the vehicle weight, and is dependent on the type of tires, their inflation, temperature, speed and other things.  Since my Corvette weighs around 3200 pounds, this gives about 48 pounds at 60 mph. This makes the Total Drag as 116.7 + 48 or 164.7 pounds at 60 mph (and 218.9 pounds at 70 mph) (and 51.9 + 32 or 83.9 pounds at 40 mph).

 At 60 mph, the total required horsepower to overcome this drag and maintain a constant speed is 164.7 * 88 / 550 or 26.4 horsepower.  (at 70 mph it is 40.9 a considerably higher drag load!)  A horsepower is equivalent to 726 watts so this is 19,700 watts of needed (or usable) output.  In one hour of driving at that constant speed, we would therefore ACTUALLY use up an amount of energy equal to 19,700 watt-hours or 19.7 kWh. (at 70 mph, 30.5 kW, and at 40 mph, 6.7 kW).  This is the ACTUAL amount of power (expressed in electrical units) that is needed to move my Corvette at a constant speed at those speeds!  Sort of amazingly low, as four kitchen toasters use up 6 kW of electrical power!

 Included in the example above is the tire resistance, which, at 60 mph, is usually around 1.5% of the vehicle weight.  For a modern 3,000 pound automobile, that's around 45 pounds of tire resistance force.  The total vehicle drag is the sum of these two (air resistance and tire resistance), which ranges from about 150 to 230 pounds force (again, for standard-shaped cars, and not trucks or SUVs).  Wheel bearings and other mechanical frictions also exist, but in a reasonably maintained vehicle, they are very small and will be neglected here.

 That was for a mid-sized car.  What about a sub-compact car?  The frontal area is much smaller, so the air resistance drag is less, and the vehicle weight is less, so the tire resistance is less, too.  Such a small car could therefore have a total drag (again, at 60 mph) which is lower than the numbers for my Corvette.  (This is why small cars can have less powerful engines!  They generally need less horsepower to travel at a constant speed.)"

[wavery]

What you must realize is that he is talking about HP to the ground. Automobiles are rated by HP at the engine's flywheel. There is a huge difference in the calculation and everything depends on gear ratios and transmission types. Only a percentage of your cars engine HP is transfered to the ground. I'm not sure what that percentage is but I would guess that it is just over 1/2 at the same RPM in high gear.