The first version of a radical new technology always gets off to a slow start — remember what they said about the first iPhone? — and so it is with the all-electric Nissan Leaf and plug-in hybrid Chevy Volt. Yet both vehicles are having an unexpected effect on their makers' bottom line. By getting people into the showroom, they’re helping to move other fuel efficient vehicles.

Just having those vehicles in the showroom can translate into sales of other models, [said Oliver Hazimeh, an automotive industry consultant]. Shoppers come in to check out the electric vehicles but then drive off with something else if they find they can't afford the premium for the new technology.

For example, folks come in to look at the Volt – MSRP $39,000 — and leave with the Cruze – MSRP $16,700 — which is the most fuel-efficient gasoline vehicle in the U.S., with MPG comparable to the Toyota Prius. ($22,000)

To continue the iPhone analogy, remember that when it came out, most people didn't even have a smart phone. In the same way, today's electrics are competing not just with other fuel-efficient vehicles, but Americans' aversion to buying fuel-efficient cars in the first place.

So the fact that the Leaf and the Volt are even bringing the efficiency conversation to the table is a victory — no doubt the first of many, as batteries become cheaper and oil more expensive.