Half a tank of each gives you E7.5 and a lower octane level (ron) than super unleaded and is cheaper and most cars just don’t need 97+ ron. My Suzuki used to run smoother on E7.5 than it did on E10 and gives a bit more get up and go.
I didn’t see any point filling up with just e5 97/99 ron. Although, put that in my older Honda civic sport and drive it so the vtec kicks in and you then notice a huge difference. For day to day stop start driving E10 is ok. E5 95 ron removal from the uk market is another forced upon us government policy that makes no difference only costs more for drivers, however you look at it.
EX30 SMER Ultra