I have 3 columns here

Car Date Mileage
d500
d500
d500
d500
4555
4555
4555
4555
and so on

dates are unique and mileages are sometimes same and sometimes more than the previous
I want to work out which car has the same mileage and which cars mileage has been same or reduced
Bear in mind that there are multiple entries for same car and need to find out the change in mileage in different entries
Excel/Access solutions are welcome
Thanks in Advance

Thanks