CNN Money: Chevy Volt to get 230 mpg rating
When gasoline is providing the power, the Volt might get as much as 50 mpg.
So what’s the lower bound at wide open throttle on a hill in Seattle?
So let’s say the car is driven 50 miles in a day.
OK
For the first 40 miles, no gas is used and during the last 10 miles, 0.2 gallons are used. That’s the equivalent of 250 miles per gallon.
Well obviously it didn’t use any fuel on the first 40 miles. I don’t need you to tell me that dividing a bigger number by a fraction will result in a larger number. Here’s some more fun mpg maths:
But, if the driver continues on to 80 miles, total fuel economy would drop to about 100 mpg. And if the driver goes 300 miles, the fuel economy would be just 62.5 mpg.
So, given these average miles per gallon when we assume no gallons are consumed in the first 40 miles, here’s a list of the marginal mileage:
0.2 gallons per 10 miles when driven 50 miles (50 mpg)
0.8 gallons per 30 miles when driven 80 miles (37.5 mpg)
4.8 gallons per 260 miles when driven 300 miles (54.2 mpg ?)
The company said it estimates it will need 8 kilowatt hours for the recharge necessary to travel 40 miles. That should cost a total of about 40 cents at off-peak electricity rates in Detroit, Henderson said. National figures from the Department of Energy suggest most consumers would pay more than that, probably around 88 cents per recharge.
One might ask, will off-peak rates remain constant?
Suppose average Joe, drives 12,000 or 15,000 miles per year.
(This may be a high or low estimate for Volt buyers. USA Today reported on a study of 359,309 vehicles over a two-year period by Quality Planning showing that hybrid owners “drove an average of 10,500 miles a year when not commuting“. It is possible that Volt buyers may alter their driving habits because of the high mpg ratings.)
Let’s say Joe always uses the battery and never needs the generator. Joe recharges his car 300 or 375 (more than once a day, oy!) times a year, pulling down 8 kWh from the grid each time. Sales estimates, courtesy of Wikipedia, are 10,000 units in year 1 and 60,000 units in year 2.
In year 1, Joe and his Volt-driving buddies are pulling down between 27 and 30 gWh from the grid, additional electrical demand previously met by a different infrastructure. Now in year 2, there are 70,000 units in operation pulling down between 168 and 210 gWh hours from the grid at night. According to the CIA World Factbook, US electrical consumption was 3,892,000 gWh in 2007. So by the second year with nothing but Chevy Volts driving at current yearly averages, Joe and his friends have increased the demand for electricity by around 0.005%, less than a one-hundredth of a percent. It would take between 13 and 16 million Volt drivers to increase electrical demand by 1%. Is it enough to affect “off-peak” electricity prices – I can’t say, but there are the numbers.
The part where I calculate true mpg on those first 40 miles
I tried for the life of me to find a simple ComEd rate sheet, but the only one I came across was almost 400 pages. Glancing at my latest electricity bill, I’m paying $0.12257 per kWh. If 8 kWh get me 40 miles, that’s $0.981 per 40 miles, or $0.0245 per mile. My S2000 gets 23.5 mpg city and Shell Premium Unleaded is about $2.999/gallon, so I’d use 1.70 gallons per 40 miles at a total cost of $5.09 – or about $0.127 per mile. That’s about 5.18 times more efficient than my car, giving the Volt an equivalent 122 mpg over the first 40 miles. Not bad, but it’s still apples to oranges when you consider vehicle cost, performance, driving habits, etc.
Concluding remarks
Henderson conceded the cost of building a Volt will be expensive, about $40,000 per vehicle. But he said the vehicle will qualify for a $7,500 tax credit, which will reduce the vehicle cost by that amount for consumers.
How valuable that tax credit is depends on your income level, but it’s clear that you are trading higher operating costs for a higher up-front cost. This is not a new concept, and is essential to capitalism. (See former note about self checkout registers replacing grocery store clerks.) Assuming all of that higher initial cost can’t be remedied through volume and other cost savings, the difference in cost between the Volt and any other ‘comparable’ vehicle would need to be allocated over the total mileage you expect to drive. Those sorts of calculations are usually too individual and subjective for me to attempt it here; however, I did that very thing when I bought my first car.