Earl Blumenauer is once again talking about about switching to a VMT tax rather than (or in addition to) a gas tax, this time at the federal level. Yes this would be a pilot program (full details here), but it will cost over $150 million to do the pilot program. It would also require drivers to have a GPS tracking device in their car, which opens a number of privacy concerns.
The article above fortunately mentions that some of his biggest campaign contributors are Honeywell International and Accenture. Honeywell is an RFID manufacturer (RFID is part of the GPS program) and Accenture is a leader in video tolling technology.
Blumenauer has his own political action committee as well, the Committee for a Livable Future, and Honeywell just happens to be the second largest contributor to them as well. He's best known for being very pro-streetcar (including bringing jobs to a Portland-area businesses under the "Buy American" guise) and pro-bicycle, but I don't think it's a coincidence that he's pushing for something that is so anti-civil liberties that will just happen to benefit major campaign contributors.
Slashdot has a great discussion about the topic as well. I understand his concern about potentially dwindling tax revenues from having more fuel-efficient cars, but pushing for a tracking system does not seem like something that I could see people supporting.
There are also numerous potential technical problems with the proposal, but there are also a number of Pacific Northwest businesses (hint: Garmin acquired Morrow, an avionics-related company started in Salem, and Garmin employs people in Newport, Salem and Portland) that would likely see a large windfall from this coming through. I have to wonder if his motives are in any way legitimate, or just based on making money for contributors to keep him in office.