Tier 4 Battlefield Hardline

So I've been looking around the internet and saw that basically the only way to get to tier 4 is to go on an empty server and drive a Hotwire around the whole time. I decided that I would try to get tier 4 the honest way, so I played a game of conquest and got an operator score of 13,000 with over 50 kills; still no tier 4. I was shocked and a little annoyed because it is very hard to get higher than that. Is there an alternative to just riding around with a boost on? Like capturing points or playing a specific game mode? Thanks.