General Motors caused a stir Monday with the bold announcement that its gas-hybrid Chevrolet Volt, which is scheduled to hit the road in a couple of years, will get the equivalent of 230 miles to the gallon.

There is no question that the Volt's technology is new, although it does borrow elements from diesel electric trains. Unlike regular gas hybrids which run on electric motors in town and on gasoline engines on the highway, the Volt runs on electric power all the time.

Its motor can take it 40 miles between charge ups. Should it need to go further, a small gasoline engine generates electricity to recharge the battery - just as a diesel engine creates the electric power to move a diesel-electric train engine.

However, GM's claim is muddled because it said it applied to city driving only, which is where the electric engine excels. It is also not clear whether it included recharging implying that it would be running exclusively on electricity.

And Nissan took some of the wind out of GM's sails by claiming that its all-electric Leaf, which it plans to put on the roads last next year, would get 367 miles to the gallon in city driving.

At the same time, GM said the typical Volt driver would pay $2.75 to drive 100 miles based on electrical utility charges. But as Consumer Reports argued, with gas currently priced at $2.75 a gallon that sounded more like 100 miles to the gallon.

In any event, 100 miles to the gallon is very good fuel economy and even if GM's announcement was based on fuzzy logic, it focused our attention on just how close we are to the much anticipated move into the electric economy.

Peter C.T. Elsworth.