This comes at a cost though, because they also make the machine consume more power, and more power means more pollution, at least while you're using Steam Engines for power generation.
The Efficiency Modules are pretty straight forward. They decrease the energy consumption of the machine they are inserted into. Not only does it decrease the energy consumption, it also lowers the pollution produced by that machine, because energy (at least while using Steam Engines) causes pollution. So by lowering the energy consumption by say 50%, the pollution from the power it uses will decrease by 50%.
Now while these statements aren't incorrect it is also safe to conclude a new player reading them will not arrive at the understanding that modules also directly increase or decrease pollution created by the machine. In fact to the contrary they are likely to believe you only get an increase or decrease in pollution if you are using steam power and that modules must have no effect on direct pollution.
And this is a case where the wrong understanding is badly wrong as there are many cases where the direct effect on pollution is much greater than the secondary effect. For example with the Electric Mining Drill using an eff1 module will reduce pollution from the mine by 2.7 and the pollution from steam power by only 0.45, in an Assembler 2 the eff1 module will reduce direct pollution by 0.72 and pollution from steam power by an almost equal 0.69.
I also quibble with this statement from the combat section:
Tanks also have very high health and resistances so they are quite sturdy and can take a lot of hits. Since they have a very high impact resistance you can actually kill things like Spawners, some Worms or even trees by simply running straight into them with enough forward momentum (picture below):
(my italics) you don't need any forward momentum with the tank as it also makes a mighty fine bulldozer, all worms can be bulldozed, with big worms it's a little reckless but definitely a thing you "can" do, and what's with "even" trees?, even the car can run down trees and anyone who plays the campaign will know this.It actually reads better and is more accurate with those parts simply deleted:
Tanks also have very high health and resistances so they are quite sturdy and can take a lot of hits. Since they have a very high impact resistance you can actually kill things like Spawners, Worms or trees by simply running straight into them (picture below):