I haven't used my car in a while. The last time I refueled was back in December. I've used it a couple of times but nothing very significant, so I have over 30% of a tank left.
Yesterday I drove it "hard" (kept it for a few minutes at 6K RPM, 120kph in third gear), and then drove around for 1 hour on the highway.
The gauge didn't even move. It's a 1.6L engine, car weighs barely 1000kg, so it's quite fuel efficient.
I did not notice anything strange while driving it. It didn't knock, didn't misfire, it was as "powerful" as I remember.
Should I be worried about this fuel?