This question already has an answer here:
I have a 2014 Suzuki Alto K10 Petrol (1000cc engine). The mileage so far has been fairly low <10k kms. The fuel efficiency is abysmally low ~8-9 kmpl. This average is running in strictly local conditions, heavy and slow traffic.
Someone suggested an Italian tuneup for the car. Essentially running ~100 kms on the highway at a fairy high speed >90kmph. This will supposedly open up the engine and will give a better average.
Before I actually spend the time and effort on the Italian job, question:
Has anyone tried this technique before and how effective is it?