SELECT 
    CASE [Model] 
       WHEN 'Mountain-100' THEN 'M200' 
       WHEN 'Road-150'     THEN 'R250' 
       WHEN 'Road-650'     THEN 'R750' 
       WHEN 'Touring-1000' THEN 'T1000' 
       ELSE LEFT([Model], 1) + Right([Model], 3) 
    END + ' ' + [Region] AS [ModelRegion] 
   ,(CONVERT(int, [CalendarYear]) * 100) + CONVERT(int, [Month]) AS [TimeIndex] 
   ,SUM([Quantity] ) AS [Quantity] 
   ,SUM([Amount])    AS [Amount]
   ,[CalendarYear]
   ,[Month]
   ,[dbo].[udfbuildiso8601date] ([CalendarYear], [Month], 25) AS [ReportingDate]
FROM 
   [dbo].[vDMPrep] 
WHERE 
   [Model] IN ('Mountain-100', 'Mountain-200', 'Road-150', 'Road-250', 'Road-650', 'Road-750', 'Touring-1000') 
GROUP BY 
    CASE [Model] 
       WHEN 'Mountain-100' THEN 'M200' 
       WHEN 'Road-150'     THEN 'R250' 
       WHEN 'Road-650'     THEN 'R750' 
       WHEN 'Touring-1000' THEN 'T1000' 
       ELSE LEFT([Model], 1) + Right([Model], 3) 
    END + ' ' + [Region]
   ,(CONVERT(int, [CalendarYear]) * 100) + CONVERT(int, [Month])
   ,[CalendarYear]
   ,[Month]
   ,[dbo].[udfbuildiso8601date] ([CalendarYear], [Month], 25)