The idea first emerged nearly 10 years ago as Oregon lawmakers worried that fuel-efficient cars such as gas-electric hybrids could pose a threat to road upkeep, which is paid for largely with gasoline taxes.
This is a really stupid argument because those lawmakers should know that nothing wears out a road like a truck. If there were no trucks, overland roads would need almost no maintenance. In Germany, a lot of Autobahn road paving originally built by the Nazis in the 30´s survived nicely until the 70´s when truck traffic started to increase dramatically. Nowadays, the surface has to be replaced every couple of years even though the material is a lot better than 70 years ago.
Hence, mileage of trucks should be taxed. I can´t see privacy abuse if a truck is GPS-tracked. Trucks are usually GPS-tracked anyway by the company owning it.