Originally posted by Otto Pilot:
I actually liked those with my old truck. The engine was tight and when it was tested in a facility it was clean as can be, well below the minimums for emissions, which was pretty awesome for a 20 year old engine. Unfortunately one sensor buried deep in the engine was faulty and sending out bad readings which caused my Check Engine light to come on. That's a fail for emissions test even though 2 different mechanics said it was not affecting the engine at all.
Finding those drive by emissions tests kept me driving until the truck wound up on its back. So, in this case, I suppose, government intrusiveness saved me a bunch of money.