The basic app is like this

Fuel entry form - here one enters each time the car is fueled (let's say inserts date and liters)

Car performance - here one enters car type, consumption and client charge 

Daily mileage - here one inserts counter mileage of selected car each day (maybe even inserting empty miles and loaded miles, each having a certain income for the driver / company)

Ideally one would need have two additional forms, spare parts and services - allowing driver to enter all cost involved with car, to monitor real profit.

The reports i would need from this:

-daily performance : today mileage - yesterdays mileage = daily performance 

-daily earning gross: daily performance * car per km value found in car form

- performance weekly / monthly report : sum of last xx days or sum of from - to date range

- cost report - sums of parts / services cost as above

- net profit calculation: gross earnings less - cost report

I can manage all the work with form creation, but am a bit stuck how to unite all teh data together and eecially how to make calculation reports. Is something like this even possible in zoho creator?

Thank you for any suggestions.

Matt