Armored locomotive does produce exhaust as it's moving in manual mode, but in automatic mode it does not.

Thank you for the report. There is no bug. Armored trains DO make smoke in manual and automatic modes. It is just less obvious because the trains accelerate much faster, and only make smoke when they are actively burning fuel (which they stop doing so quickly, once they come to speed).

You can test this yourself by making a 1-20 train with an armored locomotive.

I may turn up the smoke a bit in the next patch, but it will still be less obvious than for vanilla trains.

You are right, sorry. Guess the wind was so strong I didn't see the smoke. No need to change nothing.