GM wants a 230MPG rating from the EPA

Until you can go 30 miles with zero gas in a factory Prius you are comparing two different animals here. In addition the Volt is the fastest all electric speed of a production vehicle other then of course the Tesla.

I also look forward to a factory Prius plug in as it could also run with zero gas as well. Toyota could beat GM to the punch by selling to the public a plug in Prius before the Volt is available. Competitition is good.

 

The 74HP from the engine is probably enough to propel the car forever (until it runs out of gas) at 90-100mph without using the battery at all. As I mentioned the Prius can go forever at 107mph with 76HP, but the Volt is going to be larger and so will probably have a lower top-speed on engine alone.

When the electric mode finishes the battery won't be completely empty - (I have seen values of around 30% full). Some of this energy can be loaned for short term needs exactly as in the Prius.

So if you want to drive 300 miles at 80mph - I don't think the car will prevent you.

At times, such as when accelerating, the battery will be discharging (just like the Prius) and when the opportunity presents itself (braking, going downhill etc) it will be recharged to the 30% level (just like the Prius).

If you go up a very long climb into the mountains - yes you may get to the point of running out of electrical power and so be limited to the engine power available (Just like the Prius).

Overall I think the compromises may be no different than what people accept with the Prius.

kevin

 

This is not perpetual motion - the amount of energy you put into the electric motor will be less than coming out of the engine.

However there is nothing saying that you can't take 74HP out of the engine plus an additional 76HP out of the battery for five minutes while climbing a hill (This is just under 5KWh out of the battery) providing you then replenish the battery on the way down the hill or while cruising.

kevin

 

Vehicle weight only affects acceleration and deceleration; vehicle weight does not affect the ability of the engine/motor to maintain speed at 70mph. At 70mph, only drag force, rolling friction/uneven pavement, and internal friction within the drive train affect the amount of power output required by the engine/motor to maintain speed. I'm sure you already know this though.

Addressing the weight factor, if driven properly, that extra 20% in momentum can be recaptured with regen braking.

Where the 20% kills both of these scenarios is when you are driving on an uphill incline.
I think future vehicles should include an additional generator that can be engaged/disengaged with an electronic clutch. This way, when you are driving down a steep grade, or braking beyond the threshold of your current motor/generator's capacity, your vehicle's computer can engage the second generator.

 

Knowing how much torque the electric engine has.. I'm surprised the electric motor cannot reach 60 faster?... it barely beats the Prius which is using the ICE for most of its power?
This also makes me suspicious of that the true gas mileage will be since it has such a hard time getting that weight to move any faster.

Nevertheless, 20% more weight is pretty significant.
I think you miscalculate the mileage hit will will make.

When your driving a Diesiel truck and only getting 10-15 miles a gallon, 20% is not so bad, but when your up around 50mph, 20% is much more significant.

 

If your right, it will be a viable alternative, but I think its not viable enough to draw 40K best case scenario... but who knows... maybe they will sell like hot cakes... We'll see!

 

The more you weigh, pavement friction increases as well as internal friction.

 

230 MPG??? go ahead... my Zenn is rated at 240 MPG!!

 

Are we dragging some part of the car on the pavement? The only issue here and its not a big one is increased tire size (if used) and higher rolling resistance. Its not nearly as much of an issue as aerodynamic drag which weight has no bearing on.

 

And we used to make fun of the people who drove down the street with their gas caps open. Now we are going to have to dodge extension cords.

 

I guess you never lived in place where everyone use engine block heats/battery warms/ interior heaters/, you would see this a couple times a month

 

These are the SAE recommendations to add to EPA estimates, to help reduce the misleading caused by numbers just like we have already seen from the "230" hype:

• a cycle at -7 C degrees (19 F) with the Heater running
• a cycle at 35 C degrees (95 F) with the A/C running
• a cycle of highway-only cruising in CS (Charge-Sustaining) mode

.

 

Good point. Whatever system they arrive upon, it needs to be something that consumers can verify on their own. Right now, my grandma can fill her gas tank, look at her odometer, and drive her car until it literally stops, and then calculate her mpg. With electrics, consumers should have a way that they can verify consumption on their own. "Miles per charge" would make sense, and then have a separate rating for MPG.

 

Many people have a distorted understanding of torque - the torque of an internal mechanical component (the electric motor) is irrelevant from the point of view of performance.

For example in the Gen3 Prius the torque of MG2 was halved form Gen2. Did that reduce performance? No, because the gearing was changed.

The only important measurement is how much torque is there at the wheel (and the wheel diameter) - this defines the tractive effort that will accelerate the car.

This is one area where the Prius is very wimpy off the line - even though the 285ft/lb torque of MG2 sounds impressive it is only multiplied by a factor of about 4 to give about 1200 ft-lb at the wheel, the engine adds ~250 to give a total of about 1450 ft-lb at the driving wheels.

A Yaris - only has 100 ft-lb engine torque but with the 4:1 final drive and about 4:1 in the gearbox it will get about 1600 ft-lb of torque at the wheels, for a car that weighs about 20% less than the Prius.

Back to the Volt - one way of calculating the potential 0-60 time is to calculate how much kinetic energy the car must be given then given the power output of the propulsion system this gives a best case acceleration time.

Assuming the mass is 3600lb (1600KG) and the final speed is 60 mph (27m/s) the kinetic energy will be 1/2 m v**2 = 583000 Joules.

If the maximum mechanical output of the Volt is 150HP this equates to 112kW.

At 100% efficiency this would only take about 5.2 seconds.

An efficiency of 65% would result in a time of about 8.5 seconds.

Without more information it is difficult to estimate what the efficiency would be, i.e. how much are the losses.

kevin

 

The EPA is working and HAS been working on the MPG thing for cars like the Volt for a while now and: "The EPA is currently in long, soul-searching meetings to agree on a standard; a draft proposal should be submitted by year’s end. Whatever the specifics, GM expects the Volt to carry a fuel-economy rating of well over 100 mpg"

That was taken from this article here:

The Truth About EPA City / Highway MPG Estimates - Feature - Auto Reviews - Car and Driver

and the discussion is here:

http://priuschat.com/forums/other-c...uth-about-epa-city-highway-mpg-estimates.html

 

Up here, at -30 and colder, it's a constant menace. Especially little old ladies blissfully driving down the street, the extension cord whipping behind their car, pedestrians bundled up like Nanook of the North trying to avoid the snake-like end of the cord, etc

 

Based on local electric rates (after taxes), I figure the Chevy Volt gets the equivalent of 71 MPG when electric (that's based on 15 cents per KWH, winter park florida after taxes). If the above number of 22 MPG for gas range is true.

That means in a 230 mile drive, the Chevy Volt will cost you (in my neighborhood):

40 Miles Electric: $1.20
190 Miles Gas: $21.89 (8.26 gallons of gas)
Total 230 miles cost: $23.09
(this is assuming $2.65 gas)

At $2.65 gas (EPA loves that number and very close to current price here in FL), that means in a 230 mile drive the chevy volt will give you a gas mileage of: 26.4

For you math folks, that's (230miles/(total cost of gas/$2.65 per gallon))

Hmmm... 26.4 MPG is not 230 MPG...

Think I'll stick to my Prius... I know even if I drive really fast I'll at least get 45MPG in a 230 mile drive, or much much better if I drive wisely. ;-)

Rick

 

Oops, I was too generous, I gave the Chevy Volt 23 MPG, but it's actually 22 MPG. That changes it to 21 MPG.

 

Re: Chevy Volt - 230MPG EPA City?

Thankyou Legend. That pretty well sums up GM. Hope you find a more fulfilling job. Aptera may be hiring.

 

It's not going to get 22 MPG, not if people drive it with a little bit of sense.

A lot of people put a lot of work into the studies that show most people don't drive more than 40 miles a day.

People who use the Volt properly will have to worry about the gas in the tank going bad before they'll even consider calculating the MPG unless they are just hypermilers trying to prove all this stupid naysaying wrong. Anyone who takes the Volt cross country is defeating the purpose of the car.

And honestly!... How many of you go across the country or over 300 miles regularly. I know for a fact that there are more people who DON'T drive that far than who DO.

You guys can extrapolate, triangulate, multiply and divide yourselves silly but I think deep down you all know full well if you had this car you'd figure out a way to get huge mileage numbers that would blow the minds of all the mainstream hybrid "lovers".