Welcome to the forum. A multi Fiesta owner!
That’s kind of unusual to have a petrol and a diesel Fiesta. We never got a diesel version of Fiesta in North America.
How does the diesel compare with the petrol for maintenance costs and overall daily convenience of use?
I had several diesel powered Ford Escorts and a couple of Ford Tempo’s with the 2.0 Mazda Diesel engines. They were sluggish in urban driving but really, really great for long distance trips. The downside of them was two above average cost oil filters and the more frequent replacement of oil, air and fuel filters.