There are some consumables that are only available to a limited number of tanks depending on their nation and the type of engine they're using. They can give +5% or +10% engine power, some also increase turret traverse speed. I have to admit that after 37.000 games, i've still never really used them and often forget they even exist. But it doesn't really sound that bad on paper to replace a fire extinguisher with an engine boost. It's probably inferior to food, but i never really use food anyway because 20k credits per game doesn't seem worth it, but 5k is not too bad. Which tanks are you using them on? I'm playing the 268 V4 a lot right now and i haven't been set on fire once in like 50 games, would boosting the engine power be worth it for ramming, for example?
Also, how does that consumable work that gives a 10% boost but damages your engine? I noticed that you can turn it on and off in battle, does it have like a set amount of seconds you can use it until it breaks?
Source: https://www.reddit.com/r/WorldofTanks/comments/sfnrbm/engine_power_consumables/