I do like to keep track of my milage, using a phone app for that.
On my "new" Kia CRDI:
5.44 l/100 km (43.24 miles per US, 51.91 per UK gallon)
Average cost per 100 km: 7.51€ (15.68$ per 100 miles)
After 17 fillups, I burned 545.37 litres of diesel (144.07 US gallons)
I've traveled 10,0019.9km (6226.08 miles)
And I've spent 753.38€ (976.83$) on fuel so far.
All since 23rd of September...