Big Green Claims for the Fisker Karma Supercar

(MoneyWatch)  The Fisker Karma will be at the Frankfurt Motor Show next week, and the Irvine, California-based company is claiming very strong green credentials for its ultra-fast (zero to 62 in six seconds) plug-in hybrid supercar. Using Society of Automotive Engineers (SAE) calculators, Fisker says it gets 67.2 mpg. This is far from a number to take to the bank, since there's no settled way of calculating mpg for plug-in hybrids, and the EPA hasn't rated the Karma. The company thinks it will eventually get EPA rated at better than 100 mpg.

The company also claims that the Karma produces just 83 grams of carbon dioxide (the principal global warming gas) per kilometer, "less than that of today's cleanest production cars and 75 percent less than that of competing vehicles." But what cars compete directly with the Fisker Karma?

If 15,000 Karmas were sold annually, which is certainly Fisker's intent, 248 million gallons of gas and 2.3 metric tons of CO2 would be saved through 2016, the company says. Running the car as a gas-electric hybrid will cost an average of seven cents a mile , using a methodology that probably does make sense.

But a lot of Fisker cruising will be all-electric. Karmas will have switchable "stealth" modes, meaning that the owner/operator can opt for battery power on demand. Fisker sees this as a boon for European buyers, who will be able to operate their cars freely in the traffic-restricted Low Emissions Zones (LEZ) in 70 cities in eight countries.