That Extreme Prejudice map is big enough I'd say.
With regard to poly counts, you're right of course, frame rates DO suffer, but I think it should be for a mapper to decide whether or not to put vehicles in, because the mapper has the most influence on poly count, and therefore knows.
The influence of drivables does not have to be so big: if you put just one or two vehicles in, you still get a reasonable performance, and since Inf is a tactical game anyway, it wouldn't make sense to put a large number of vehicles in anyway. (Well, not until there are a few hundred bots running around the level)
When looking at FPS games in general, these always tend to push the hardware, resulting in people upgrading. This is annoying for people who have fairly recent machines, that turn out not be quite up to the job I admit, but it is reality, and it has been for the last decade.
So when you put vehicle support in, it's with an eye on the future - even though I think many systems from say two years ago will handle vehicles without much trouble.
Vehicle support is a topic that pops up regularly on these forums, and I think there is a consensus among regulars that it would be nice to have the option
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