I once did 123 MPH (198 KPH) on I-15 in my Caprice (speed verified by GPS). And I didn't even reach the top end, I could have gone faster. (I was in a fairly remote area, 8 lanes wide with a large median and good shoulders, very little traffic and a good line of sight, so it wasn't totally reckless.)
I'd like to find out just how fast my car could go, but I don't think I'll be trying it on the freeway again. I'd like to go to Muroc or Bonneville or someplace long and flat and just put the pedal to the metal.