Another Hymotion PHEV in consumer's hands

I think it depends what you are after. If all you care about is getting off oil, than I would agree all that matters is battery range. Where it gets tricky is when you start caring about overall efficiency. For example, you could build a PHEV Hummer that would get infinite MPG for a certain period of time. Is it really informative to rate both a PHEV hummer and a PHEV Prius as Inf MPG? Even if they both have enough battery to complete the current EPA cycle without using any gas, I think its clear one is more efficient than the other. There needs to be a way for the consumer to aware what the fuel usage will be on longer trips, or on days when they forget to (or are unable to) plug in. They also need to know how much electricity will be used to offset their gas, as electricity while cheaper than gas still isn't necessarily free or clean. The trick is to come up with a simple, easy to understand and compare metric that takes all these into account in a fair and informative manner. Thats easier said than done.

Rob

 

EV Kwh/mile at 60 mph.
Empty to Full Battery Charge in Kwh
Straight petrol city mpg
Straight petrol highway mpg

I don't see why a hummer should be less efficient than a Volt in EV mode. Just more work/distance.

Even the average US consumer who would fail trying to distinguish work from power will be able to grasp that a kWh is an amount of electrical energy, just as a gallon is an amount of fuel energy. They already know that a gallon of fuel costs them $x, and is good for Y miles. Soon they will be able to figure out that a kWh costs them $q, and is good for R miles. The car dealer will help them with division, to come up with a cost/distance apples to apples comparison. I expect to see little cardboard wheels to help out the poor consumer who has a blend of EV and petrol consumption.

 

Except that vehicle efficiency is typically (if incorrectly) measured as energy expended over a distance; Miles per gallon, Litres per 100km, Wh per mile, miles per kWh etc. While not a technically correct physics work in work out definition of efficiency, a technically correct definition would give the vehicle credit for moving itself down the road, when the desired output is how efficiently it moves you down the road. The fact that it has to move itself down the road is a key factor in a vehicles inefficiency. Doing more work per unit distance requires more force. Applying more force given a fixed chemical-electro-mechanical or ICE efficiency requires more energy expenditure. Expending more energy per distance fits the popular definition of lower vehicle efficiency.

While your metrics cover the basics, I think even a fairly technical person would have a hard time predicting their fuel costs and pollution output based on those numbers alone. Some PHEVs will accelerate in mixed mode, using more fuel and generating more pollution in city driving but increasing their electric range. Others will use full electric for acceleration making city driving cleaner, but getting much less than their 60mph cruising range before reverting to full ICE. Some PHEVs will run full electric at freeway speeds, using no gas until the battery runs out, then running gas only. Others will run in mixed mode on the freeway, using less gas for a longer period of time. Some PHEVs will use the ICE more during very cold or very hot weather to protect the batteries or run accessories, or will always run a warmup cycle to make sure the ICE is ready to use. Others will force pure electric even under conditions that may be detrimental to battery life or comfort. The variety of ways in which manufacturers may implement PHEVs, and their highly trip length dependent nature is going to make things complicated IMHO.

Rob

 

Well, since current petrol EPA is +/- 50% accurate for the gamut of US drivers, I don't feel like being too picky.

As for the "problem" of blended driving, this only comes into play when the driving distance between charges is less than pure EV calculates out as. I'll leave that for GM to hype, since it is trying to make a mountain out of a ant hill.

 

Fair enough

Rob

 

interesting question and i rarely dispute anything hobbit has to say, but on my EV, there is two ways you can look at "mpg" when part of the "gas" is coming from the wall.

1) straight energy...not really a good way since conversion losses vary greatly...but if using that figure, the mileage is reportedly around 254 mpg...

2) cost (what i use)... if using that, then you must meter the power used to charge your pack...i have a Kill-a-watt meter... bought it online for like $20-30...dont remember how much it was exactly other than it was an insignificant amount. it meters the amount of charge, charge rate, voltage, wattage, etc...

its a very simple device, cant chart it (at least my version you cant, i do understand that more capable versions are available for a price)

but i take my to KWH used...figure my total electricity bill based on that (my rates are 7.2 cents per kwh but taxes, base charge, yada yada, bring my cost to around 9.2 to 9.5 kwh) to figure my cost per mile...

now i am running about 2.1-2.2 cents per mile compared to my reg Pri getting 52-55 mpg which is running between 7.1 to 7.9 cents per mile

now obviously, what anyone gets is going to be determined by how much highway driving they do. with my commute, i could easily go MONTHS between pips (yes PIPS!! not tanks) because our commutes are short. most of our trips are short as well. with the mileage boost on the Hymo pack, that would reduce our gas consumption to under a gallon for even the longest of our normal "out of town" ventures

 

probably already a lot of responses to this post im guessing, (havent read them all yet) but had to put my 2 cents in

if you own a Pri, you are not that concerned with money, at least, let me restate, if you have owned your Pri for more than say 3 years...

because when i bought my Pri, saving money was the farthest from my mind. how could i save money by spending $25,000 on a new car? by getting good gas mileage?? ya right... could have bought a corolla for $9,000 less (they HAD incentives back then...not so much any more) it would take DECADES to get my money back

no i bought the car because it was cool looking (yes im one of the rare ones who likes the unique look of the Pri)

it was cutting edge technology, SKS, hybrid MFD, it all played a part

money had nothing to do with it... at least back then... i had no idea that buy ing a Pri would become one of the best "investment" opportunities i could buy...

what other car could i buy, drive for 2-3 years then sell it for what i paid for it??

but the most important part is the immediate reduction in oil consumption without sacrificing transportation needs or methods...lets face it... imm, its probably too late already. by doing what i am going, i am hopefully starting a movement to "snatch victory from the hands of defeat"

i bought an EV for $16,000 after taxes...look at my sig...at the rate im saving money on gas, it will take a half a century to break even...and EV's historically do not resell very well because everyone is paranoid over having to replace the batteries (currently around $900 if getting upgraded pack i currently use...so not all that much, but try convincing someone who knows nothing but all the bad press given EV's from car companies, oil companies, gas companies etc)