What makes a car fuel-efficient? Hybrid technology? A sophisticated direct fuel injection system? Turbocharging? Downsizing the engine? Well, all of the above, but we shall not forget aerodynamics. The less drag, the less energy the car will require to move. Still, it’s a tricky science, because it mixes technology with design. You want a car to be streamlined, but you also want it to look good. More than that, there’s also the problem of noise. Bad airflow can be heard inside the car, and it doesn’t make a pleasant sound. Ford talks about it in the video below.

The new Focus has a drag coefficient of .27, a great improvement compared to its predecessor which stood at .30. A Prius is better with .25 but the Prius has a special look which doesn’t please everybody. It also appeals to a different, narrower customer group than the Focus, which Ford wants to please most people.

As an affordable basic sedan for the average driver, the Focus is simply excellent. No other car has a better drag coefficient in this price range, besides an hybrid like the Honda Insight. That is quite impressive because, if I expect hybrid cars to make a big step on the road to greener cars, I know that hybrids only appeal to a minority. All the cars must make progress, starting with the bigger sellers like a Focus, which does just that with this streamlined body (and engines with direct fuel injection).

So Ford’s going in the right directions, and I hope all the others will follow. No new car should have a drag coefficient superior to .30 in 2011. Don’t you think?