Welcome to the forum, Silent Blood!
I agree - it's a decent but not a stunning result for the 1.2L Mirage, considering the late winter temperatures, non-LRR winter tires and basic eco-driving.
I'm sure the car is capable of 80+ MPG US / 2.9 L/100 km using more extreme techniques in milder weather conditions.
I'm looking forward to reading your fuel economy
adventures with your old BMW 523!