Yes, they use a small enclosed box with a very restrictive paper filter. They do havefiltration figured out.
Gidyupgo, you may remember 20-25 years ago that turbo diesels were not the norm. They always got better mileage but with the introduction of the turbo they added power (before they were dawgs) and they kept their good mileage. Look, would you agree with the following. Over the past 20 years car manufacturers have increased power AND fuel economy? If so, then there has to be more to power than fuel to air ratio and creating a bigger bang. Maybe apples to oranges, I'm not arguing that. Just a point of view.