Something that has always annoyed me is that a ship with a motor and a few weapons always has a disadvantage to a ship with no motor and all weapons.

Having a motor should have a disadvantage in combat - however, I think it should also have a small positive effect so that the speed of the ship isnt just completly ignored in combat.

You could have a system where for each 1 speed that a ship has over the enemy, it gets a 10% chance of getting a free hit at the begining of combat or something.(or maybe a damage % boost to the first round or chance to hit/be hit %)

This then leads into my second thought - motor size (and possibly price) should be greatly reduced for tiny and small ships and slightly increased for large and huge ships.

This would a) keep smaller ships viable due to the new combat mechanic of taking relative speed into account and mean that people would actually use tiny and small ships as scout ships rather than wack a load of motors onto a cargo ship (something which is meant to be slow)

Now, I know that the combat mechanic part wouldn't be easy to implement but I really think it would be worth the effort spend on it and make the overall combat system deeper!