[DXCategory("Behavior")]
public event FilterPopupExcelDataEventHandler FilterPopupExcelData

<DXCategory("Behavior")>
Public Event FilterPopupExcelData As FilterPopupExcelDataEventHandler

pivotGridControl.FilterPopupExcelData += OnFilterPopupExcelData;
// ...
void OnFilterPopupExcelData(object sender, FilterPopupExcelDataEventArgs e) {
    string prefilterColumnName = fieldModification.PrefilterColumnName;
    if(e.Field == fieldModification) {
        e.AddFilter("Fuel Economy (<color=green>High</color>)", "Contains([" + prefilterColumnName + "], '6A')", true);
        e.AddFilter("Automatic Transmission (8-speed)", "Contains([" + prefilterColumnName + "], '8A')", true);
        e.AddFilter("Manual Transmission (6-speed)", "Contains([" + prefilterColumnName + "], '6M')", true);
        e.AddFilter("Manual Transmission (7-speed)", "Contains([" + prefilterColumnName + "], '7M')", true);
        e.AddFilter("Variadic Transmission", "Contains([" + prefilterColumnName + "], 'VA')", true);
        e.AddFilter("<b>Limited Edition</b>", "Contains([" + prefilterColumnName + "], 'Limited')", true);
    }
}

Private pivotGridControl.FilterPopupExcelData += AddressOf OnFilterPopupExcelData
' ...
Private Sub OnFilterPopupExcelData(ByVal sender As Object, ByVal e As FilterPopupExcelDataEventArgs)
    Dim prefilterColumnName As String = fieldModification.PrefilterColumnName
    If e.Field = fieldModification Then
        e.AddFilter("Fuel Economy (<color=green>High</color>)", "Contains([" & prefilterColumnName & "], '6A')", True)
        e.AddFilter("Automatic Transmission (8-speed)", "Contains([" & prefilterColumnName & "], '8A')", True)
        e.AddFilter("Manual Transmission (6-speed)", "Contains([" & prefilterColumnName & "], '6M')", True)
        e.AddFilter("Manual Transmission (7-speed)", "Contains([" & prefilterColumnName & "], '7M')", True)
        e.AddFilter("Variadic Transmission", "Contains([" & prefilterColumnName & "], 'VA')", True)
        e.AddFilter("<b>Limited Edition</b>", "Contains([" & prefilterColumnName & "], 'Limited')", True)
    End If
End Sub

readonly static char[] separators = new char[] { ',', ' ' };

void OnFilterPopupExcelData(object sender, FilterPopupExcelDataEventArgs e) {
    // Create a collection of tokens based on data values.
    var tokens = new HashSet<string>();
    for(int i = 0; i < e.Values.Length; i++) {
        var parts = ((string)e.Values[i]).Split(separators, StringSplitOptions.RemoveEmptyEntries);
        for(int j = 0; j < parts.Length; j++)
            tokens.Add(parts[j]);
    }
    // Remove the default data values from the filter menu.
    e.ClearData();
    // Populate the menu with the created tokens.
    foreach(string t in tokens.OrderBy(x => x))
        e.AddData(t, t);
}

Private ReadOnly Shared separators() As Char = { ","c, " "c }

Private Sub OnFilterPopupExcelData(ByVal sender As Object, ByVal e As FilterPopupExcelDataEventArgs)
    ' Create a collection of tokens based on data values.
    Dim tokens = New HashSet(Of String)()
    For i As Integer = 0 To e.Values.Length - 1
        Dim parts = DirectCast(e.Values(i), String).Split(separators, StringSplitOptions.RemoveEmptyEntries)
        For j As Integer = 0 To parts.Length - 1
            tokens.Add(parts(j))
        Next j
    Next i
    ' Remove the default data values from the filter menu.
    e.ClearData()
    ' Populate the menu with the created tokens.
    For Each t As String In tokens.OrderBy(Function(x) x)
        e.AddData(t, t)
    Next t
End Sub