Hi,
first of all, I love your mod.
Second, is there a way how to improve Ravens speed?
Maybe some configurable value that can be changed.
Or a MK2 and MK3 versions in later updates?

In Factorio max speed is calculated with a so called "friction" factor. The only way to increase the maximum speed atm would be by decreasing this friction-factor, and you would have to modify the code line yourself.
If you wish to do so, go to where your mods are located (appdata\Roaming\Factorio\mods), find the Raven mod and unzip it. Or download it from here and copy it later.
Inside you will find a file called "data.lua" , open it with an text editor.
Search for this:
type = "car",
name = "raven-2",
Few lines later you will find:
friction = 12e-4,
Lower this number and you will get higher speeds, make it 0 and you will have infinite speed. (Btw 12e-4 = 0.0012)

As far as MK2 etc. goes, I think Maroder wants to fix all the problems first, before somethink like this happens.

Thank you very much for your answer.
Simple and comprehensible.
I did as you said and it works like a charm.

I didn't know it is possible to change stats of entities this way.
I'm going to take a closer look at it and maybe learn something new.
Or break it down.
Anyway, thanks again.