I hear you man! I think it matters very little if one writes out Civ V or ciV so for clarity sake I think Civ 5 should be the standard as it is as clear as anything and still very short.
ciV is what is used by people who smile every single time they type it because they not only managed to abbreviate an abbreviation, but they also managed to work in the roman numericals while cleverly distingiushing between the name and the number by the use of capitals... Oh, the joy of saving yourself an extra keystroke ot two must be nothing short of extatic! Not only does is set oneself apart from the majority of the people on the internet who actually have to type in another space and then a 5 where one might save oneself the trouble by simply holding shift, but now one can even look smart amongst civfanatics by simply hopping on some bandwagon that left the station years ago. How original and clever it must seem!
Fun!