10-year cost to own a Volt ($40,000) vs. a $30,000 car that gets 32mpg is
about the same, with a commute between 30-100 miles/day.
If gas goes to $6/gallon, you might save $8000
over 10 years for a 30 mile daily commute, $12000 for a 100 mile daily.
If you use a complete solar setup that actually works, you might save $5000
over 10 years, minus your start-up costs for the solar (probably well over $5k).
Here's a neat Volt Calculator:
http://www.digifixpix.com/volt/volt_calc.asp
The Volt was fun and a great car to drive, especially since it had gas generator so you had no range anxiety. I would go a month or more without a fill up. But I was also paying on a $40k car, not a beater.
It's a great niche vehicle, with little economic value.
Padre