Increased Speed When There is No Collision Impending
Speed limit is 100m/s because of collision mechanic calculations in Space Engineers. This means that if you have no voxel, grid, atmosphere or gravity to hit, you should be able to move a lot faster than 100m/s.
I suggest; if a ship moves in space with at least 3km away from any voxel, grid (except subgrids), atmoshpere or natural gravity, it should be able to increase its speed up to 1000m/s.
If a ship that moves faster than 100m/s becomes close proximity to any voxel, grid, atmosphere or natural gravity, its speed will reduce to 100m/s in 1 seconds.