Researchers at the Delft University of Technology in the Netherlands have found that even modern trucks are shockingly unaerodynamic. But surprisingly the big problem of the big trucks isn’t at the front, it’s at the rear.

The sharp angles at the rear, where the truck abruptly ends, cause a vacuum that in turn creates eddies of wind behind the vehicle. All of which has a negative effect on its performance. By getting rid of the vacuum researchers believe the amount of wind resistance a truck experiences could be reduced by up to 25%.

A variety of methods to improve the airflow at the back of trucks are currently being theorized, developed, and tested. It is believed that some of these could increase fuel efficiency by at least 10% if properly implemented.

More on this subject is available from the Delft University of Technology