Its not working properly, but it is possible to move up the ranks, i spent 3 to 4 days working on ranking up to the clipper and did get it, and this is what i recommend:
First, get the vulture with 2 gamboled pulse lasers and 2 chaff, the lvl 5 shield generator and lvl 4 shield bank. (this load out has proven to be amazing in conflict zones, just hokey the shield cells and chaff, and note that shield cells have a 5 second delay and only work on active shields)
Second: find a conflict zone in the empire where an empire faction is fighting an independent, (you can see the affiliation on the ranks tab on the right panel, and then look at the system factions tab to see who is at war.)
Third: every time you head to station to cash in your vouchers, (i recommend every half hour or every 500k whichever comes first) look at the bulletin board for any missions by the imperial navy, always accept these, then look for missions for the faction you are fighting for, accept any currior missions that you can, as they will increase rep in your system and the system you are delivering to, any other of their missions are up to you, fighting is giving you rep so doing their missions is not necessary.
Fourth: if you have spent more than an hour in any system bounty hunting, trading, mining or just being there, travel back to see if you have imperial navy missions there.
If you have to abandon an imperial navy mission, only do so after completing enough other missions to put your rank up anyway.
If you have been in a system a while but cant find any navy missions check other stations, as you may find missions there.
This is how i achieved the rank of baron in 3-4 full days of playing, if you are playing after work or school, or just are busy it will take longer.
Hope this helps you rank up and have fun at the same time, and remember that clipper has over 1 million in re buy costs and will need about 4 million in upgrades to use. (the starting shields and jumprange suck)