I was driving a company van on the highway at speeds of around
sixty-five miles an hour. Later on, I was found to be revving the
engine at 4300 RPMs. Although I am not usually cognizant of my RPM
rate, I try to always accelerate not too quickly. How common is it to
attain this RPM rate on the highway, and has the automtive computer
data been over-scrutinized?

A car engine operates most effectively at high speeds of revolution,
up to 4000 revolutions per minute (rpm) and beyond.

The Way It Works - Robin Kerrod
ISBN 0 7064 0986 8
page 74

You would get a better answer if you could supply Make/Model/Engine
etc for the company van.