Paul Eisenstein:

It’s as big as a Ford Focus, lighter than a Mazda Miata, and can cut through the air nearly as efficiently as a jet. But what’s likely to stand out most about the new Citroen C4 Cactus Airflow concept is its fuel economy, an estimated 141 miles per gallon.
 While that’s not quite up there with the 261 mpg Volkswagen XL1, or even the new 235 mpg Renault Eolab prototype, the new Citroen appears to be perhaps the most practical of the three models – though it remains to be seen if the French maker can actually bring the Cactus Airflow to production.
 
 Auto Insight!
 Set to debut at the upcoming Paris Motor Show, the full name of the new concept vehicle is the Citroen C4 Cactus Airflow 2L – the little fillip at the end is arguably the most significant detail, as it positions the latest Cactus concept as a so-called two-liter car. In other words, it burns that much fuel to go 100 kilometers. For metrically challenged Americans, think of going more than 70 miles on barely a half gallon of gas.
 
 To get there isn’t easy, of course – at least not for Citroen designers and engineers.