It really does depend on what kind of driving you do. If it is all steady speed driving then it is a bit easier to calculate. If you are around town it is hard to calculate, if you are doing lots of cold starting it is hard, if the temperature varies so the tyre pressures changes,
For ballpark numbers at steady speed driving, the calculator in tools is very useful.
https://ecomodder.com/forum/tool-aer...resistance.php