[onychomys]

I think it's important to remember that the national speed limit of 55 was put in as a fuel saving measure in the 1970s. Drag increases in a non-linear fashion with velocity, so you don't just use twice as much gas to go 110 than to go 55. In a world where we worry about carbon output (either from your ICE or the natural gas plant that makes your supercharger electricity), that's a very real reason why one should not drive at triple digit speeds on a highway.