The Jet Provost Mk3 is almost half the cost of the Mk4 and Mk5 Jet Provost per flying hour.
I might query this, you could read it to imply the JP3 is less than half the running cost of a 3/4?
I am unaware of any substantial difference in Fuel Burn, either at a particular IAS, or over a particular range, between the 3/4/5. Yes - at full power a 4/5 will burn the fuel a lot quicker - but so it should at +50% of thrust - and will go a lot faster / further.
NoD