If your assignment is to design a user-friendly project with GUI then yes, should not be doing data entry directly on tables. That's what forms are for.
I forgot about the Zone value. Yes, a button does make sense. However, the radio buttons need to be associated with an option group frame so that only one can be selected. Why does code set radselected to a number, the Zone field is text? Checked method won't work with radio button.
Try:
Code:
Private Sub Command48_Click()
If Me.Frame49 = 1 Then
radselected = "A"
ElseIf Me.Frame49 = 2 Then
radselected = "B"
ElseIf Me.Frame49 Then
radselected = "C"
End If
DoCmd.SetWarnings False
DoCmd.RunSQL "UPDATE CarOutStatus Set [Time Depart]=#" & Now() & "#, Zone='" & radselected & "' WHERE CarID='" & Me.Combo45 & "'"
DoCmd.SetWarnings True
End Sub