I was wondering how the Real Hybrid Mileage Database handle a vehicle like the Chevy Volt. Consider three scenarios:
1. The Volt is driven as a daily commuter car 15 miles each way to and from work. If charged nightly, no gasoline could be used making the MPG infinite if only gasoline use is considered.
2. The Volt is driven on a cross country trip without a chance for electric charging. Then the MPG would reflect the efficiency of the gasoline engine recharging the electric drive system. I have not seen any data on what the MPG might be in this driving situation.
3. The Volt is driven to as a daily commute of 50 miles each way. In this circumstance, the first 40 miles or so would be under electric drive and the last 60 miles or so would be using the gasoline engine to recharge the batteries. The resultant mileage would be somewhere between the first two scenarios.

As for the electricity use, how will that be calculated? Will every user be required to use a Kill A Watt meter or equivalent? Is there an equivalent to the Kill A Watt meter if you convert your garage outlet to 220 V for charging?

 

adding in a way to log Kilowatts consumed would help. Of course you would need a way to gauge the amount of electricy put into the pack.

 

It's a great question. Not only for the database here, but for the EPA. How are they going to handle the oncoming plug-ins? What about electric cars?

As for the database, it's easy to figure out how much gas you're putting in. It takes special equipment to figure out how much electricity you pull.

 

Here is an article from the New York Times today which discusses the EPA process for setting up fuel consumption postings for alternative powered vehicles. For the Volt, it appears that there will be a blend of the city and highway cycles recorded on electric and gasoline power.

http://www.nytimes.com/2008/11/16/au...=1&oref=slogin

 

Check the Prius database. There is at least one plug-in hybrid in the database already. GM's Volt, actually all major makers have yet to catch up with home-brew Prius plug-in conversions ... fancy that!

Bob Wilson

 

That's very cool, but doesn't that throw off the database numbers? Shouldn't a new category (vehicle class or whatever) be created for PHEV, even the modifications?

I saw he was getting great numbers.

 

I would be nice if we could create a standardized single number to measure the fuel efficiency of multi-fuel or electric cars. Maybe determine the total carbon emissions per unit and use that data to convert it to a MPG-Equivalent? This article states that 1 kWh has about half the CO2 emissions of 1 gallon of gasoline. So if a car uses X gallons of gas and Y kWh of electricity to travel Z miles, we could use the formula:

MPGe = ( X + 0.5*Y ) / Z

to calulate a miles-per-gallon equivalent. There are a few problems with this method:

• The ratio between gas and electricity varies greatly depending on what type of fuel your local power plant uses; solar, wind, and nuclear have very little CO2 emissions, while coal has quite a lot;
• There may be other factors on which this ratio should be based, other than CO2 emissions. Do you want the ratio to represent the equivalent environmental impact of gasoline or the equivalent dollar cost of gasoline?

 

Both are "green" and my preference is 'cost.' When we first started the EPA and looking at vehicle efficiency, I knew that if we made our cars and systems more efficient, they will also reduce the environmental impact. I've just been appalled at the slow pace.

Bob Wilson

 

The problem with cost is the price is ever-changing, both in electricity and in gas. Take a look at what Tesla's founders blog (I can't think of his name right now) and what he had to calculate the cost of re-charging his car. And he didn't have to worry about the cost of gas.

 

Don't worry, the EPA is having the same problem. What MPG does the Volt get? Well, it depends on the SoC and how far you drive it.