According to this Microsoft article,
Internal names are set once at the point of creation; you cannot change them later. Additionally, Internal names encode special characters in your display name including spaces not in the same way as URLs, they use a combination of underscores and x0 numbers to represent the character, for example:
e.g x0020 for " " or x003a for ":"
For example, "HR Department" would encode to "HR_x0020_Department". While this isn't necessarily essential for the end-user to know, it is essential to bear in mind when working with CAML or making API calls, as most often these are used to reference fields.
Per my test, these three columns should be defined as Car_x0020_Number, Registration_x0020_Name, Date_x0020_Covered_x0020_By_x0020_Customer.
Yes, internal name for SharePoint column is case sensitive.
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