Ok, i recently discovered hyperspace engines.
First the introduction to my question:

*"The integration of the 4th and 5th dimension allows the development of a new type of ENGINE. It is the most powerful ENGINE available." That's the description of hyperspace technology.

*"Employing spatial and temporal distortion in the engine, space is compressed which allows travel long distances in a short space of time." Thats the description of hyperspace engines.

So: i don't understand why the upgrades of hyperspace engines aren't giving me any increasement in my fleet's speed? After all i'm talking about the ENGINES upgrades here.

That's all. Thank you for your attetion.

not all ships use that engine

Schnitter is correct. To speed up a ship you need to research the respective engine that it uses. Some ships use a different engine when a certain level of that tech is reached, but most use the same engine as the one required to unlock them

A separate but similar comment: your fleet will only go as fast as your slowest ship.

so you can see what Engines do what.

With each level of the Combustion Drive developed, the speed of small[Ship refitted with Impulse Drives once reached level 5] and large cargo ships, light fighters, recyclers, and espionage probes is increased by 10%.

With each level of the Impulse Drive developed, the speed of bombers(As soon as the hyperspace drive is developed to Level 8, the Bomber is retrofitted with the hyperspace engine and can fly at higher speeds.), cruisers, heavy fighters, Elite Cargos and colony ships is increased by 20% of the base value. Interplanetary missiles also travel farther with each level.

With each level the Hyperspace Drive is developed, the speed of battleships, battlecruisers, destroyers, and deathstars is increased by 30%.