Cruising speed.As far as capability,"Put the pedal to the metal". Power to weight ratio,aerodynamics and gearing all add up to you can not go fast enough to endanger any thing.BUT handling is another thing. It is top heavy, lightly sprung ,no sway bar in the rear and a ridiculously small one in the front. A very sudden lane change and you are in real trouble. You never know when a ladder or some such will fall into your path on the freeway and you have to change lanes fast.After a series of simulated trials , I decided that I would not go over 65 in any case, but it is up to the individual.
BRAKES,remember those 9''ers were barely adequate in a panic stop at a 55 freeway speed and laughable at 70.