If true, this is a very weird story. Why is DHS involved? Why is the federal government confiscating this vehicle without even testing it? In my state, auto emission compliance is checked every two years when you renew your license tabs, it has nothing to do with the federal government. And if you fail the test, they don’t impound your car, but you are given time to fix the problem. You won’t get your tabs, but they won’t take your car.
Because at it’s heart it’s a customs issue, not emmissions. The vehicles look to have entered the country illegally.
Now, I’m not saying that this is a good use for guys who could be running down illegal aliens, but as a legal matter this is a Federal matter and ICE (which is the DHS component involved) does have jurisdiction. As it’s pre-DHS predecessor (the old CBP, I believe) would have as well.