For ultimate day to day economy for this sort of use, diesel is still best, but there can be a lot of hidden maintenance costs not covered by warranty even if it's a five or seven year warranty. It's really a difference between around 50mpg for a modern 1.2 turbo petrol and 60mpg + for a 1.5 or 1.6 diesel.

Small Fiesta size hatchbacks don't tend to get things like Lane Control that can be very dodgy anyway (it was on a Volvo XC90 T8 that boasts the very latest kit). Adaptive cruise can work or can be a nuisance because it can prevent pulling out to overtake. I's think along the lines of a Mazda 2 or the forthcoming new Citroen C3, though that won;t be here until next year.