ek1 should get 400km even when redlining it all the time.
My advice change fuel filter, service the car and then try different 98 ron fuels.
I know it made a difference for mine.
vpower - 350km per tank
vortex 98 - 450km per tank
BP U - 440km per tank
i've been pouring votrex since. i change back once in a while just the test it out. Vpower seems to have some new blend that i keep burning fast