I sometimes get up to 80 mph, however in LA I can never sustain for more than a few seconds before you have to slow down for traffic.
When my wife got her first benz and she was driving on the freeway passing everybody, I asked her to slow down. She told me "See I'm going less than 50 mph." I had to point out that she was looking at the tachometer and the 50 she was looking at meant fifty hundred rpm (or 5000 rpm). She was actually going over 90 mph!!!