Was your car a manual or automatic. If memory serves the manual gives you a few more mph top speed but its a nominal difference. Top speed I quoted is a "rated spec". It will vary on vehicle and ambient conditions. Not that exceeding rated top speed is uncommon...92 500E's have been known to pull right past the theoretical limiter at 155mph on to pegging the speedo at redline in top gear past the 160 mark on the speedo. Yeehaw! Other cars sometimes have difficulty making their rated top speeds. In the real world conditions there are too many variables to say every 300E will do xxx but the factory has to rate the model's top speed as something.
Hope this helps...Lee