Enemies driving vehicles might as well be as a different enemy. Different movement, different weapons, different strengths, weaknesses. The only reason you know who is driving is when you hijack them or blow them up. Vehicles add a lot to combat, more so than a different variation on the same enemy. A brute attack you and a brute chopper attacking you are two completely different experiences.
And this is a seperate gameplay mode, they do not have to stick with story, so elites could definitely be on the list of bad guys.







