Stinky Vehicles. Vehicles can be a biter target in a pollution cloud.
"Vehicle" = cars, tanks, spidertrons, etc. NOT train pieces.

Why? If the only polluting entity on the map is a vehicle, such as if one is playing with Mobile Factory, or in Warptorio (at least early) with no polluter on the top platform, enemies will not attack from pollution. Biters will form groups and nests absorb pollution but then the group breaks apart.

Requirements:
1) Enter a vehicle.
2) Tracking should start, and vehicle can targeted as a pollution entity.

How it works:
Once a vehicle is tracked, an invisible polluter is created below it. If the vehicle moves too far away, the polluter is recreated.

When it won't work well:
Near small gaps across impassible terrain. Biters would go to one side but couldn't cross to attack the vehicle a few tiles away. This could be fixed with a setting but performance would be reduced. Ask in discussions if you want exact-tracking.

Lots of vehicles could cause a small performance tick, every second. Also fixable if anyone wants it.