All valid points, pgary, but once we start talking about the possibility of an average speed of 390 mph (through the Altamont Pass and Grapevine, no less), we should move this discussion to a Sci-Fi thread in Omni.

You should also mention:

4. Wouldn't farmers in the Central Valley hate the sonic boom once the top speed goes to 700 mph and beyond?

and

5. Won't it be obsolete with the invention of the human particle transporter?

and

6. What about Klingons and their disrupters?