Unusual Roof Attachment

During our drive into San Francisco on the I-280 Freeway that roughly parallels the U.S. 101 to the west, we’ve come across two vehicles with a strange roof attachment.

It looks like a cylindrical intake turbine that you sometimes see on warehouses.

(Photo by the wife)

Each time, the car was in one of the slower lanes, and keeping well within the speed limit. So far, we have seen a red car twice and the pictured black car once, each time on a stretch of the freeway that passes the back side of Palo Alto and Stanford University.

I can’t find anything about it in a Google search; in fact, I can’t even put together a decent set of search terms that produces any significant hits.

So … I surmise that … it’s a freeway emissions collector mounted on top of a low-particulate/low-polluting automobile, collecting data for a Stanford University study or on-going measurement of California highway pollution.

Whattaya think?