Yesterday, I wrote a piece about GM's upcoming Volt plug-in hybrid. In it, I explained that the new car may appeal to wealthy Americans who want exhibit their love for the environment, but its supposed 230 miles per gallon can't justify its $40,000 price tag from an economic standpoint, unless you plan on driving in excess of 229,000 miles. Atlantic Correspondent Lisa Margonelli has some more bad news: the Volt won't get anywhere near 230 miles per gallon on long trips.

Margonelli writes:

The charming dorks at Environmental Economics point out that the Volt gets 230 mpg when the trip length is exactly 51.11 miles, but for a trip of 200 miles the car gets 62.5 mpg, which is not much better than my diesel VW Golf, purchased used for around $15K.

That means, even by hybrid standards, for longer trips it begins to approach Toyota's Prius hybrid which achieves in the ballpark of 50 miles per gallon, with a starting price of only $22,000. This makes the Volt's $40,000 price tag seem even less justifiable.

Still, 230 miles per gallon might be achieved most of the time for those who use the vehicle primarily for short commutes. So I wouldn't completely discount the potential of the Volt just yet. But Margonelli's point reinforces the conclusion I drew yesterday: unless better technology brings its price way down, or the price of gas skyrockets past $5 per gallon, it's unlikely that the Volt will appeal to the average American.

If you want some additional pessimism regarding the possibility of rapid growth for plug-in hybrids like the Volt, check out Margonelli's entire piece.