SELECT DISTINCT 
	h.RepairSheetNr, 
	v.unitnr, 
	v.groupid, 
	v.brandId, 
	v.modelId, 
	v.version, 
	v.Type_Fleet, 
	h.close_date,

	-- you don't need this CASE because the condition already exists in a join: v.unitnr = h.UnitNr 
	-- count(CASE WHEN h.unitnr = v.unitnr THEN v.modelId ELSE 0 END) AS TotalModels
	COUNT(v.modelId) AS TotalModels

FROM Vehicle v 
INNER JOIN RepairSheetH h 
	ON v.unitnr = h.UnitNr 
INNER JOIN RepairSheetL l 
	ON h.RepairSheetNr = l.RepairSheetNr 
INNER JOIN CashFlow_Accounts cf
	ON h.Company = cf.Company 
	AND l.cashflow = cf.CashFlow_AccID
WHERE l.cashflow = '201708' 
	AND v.Type_Fleet<>'FS' 

GROUP BY 
	h.RepairSheetNr,
	v.unitnr,
	v.groupid,
	v.brandId,
	v.modelId,
	v.version,
	v.Type_Fleet,
	h.close_date,
	
	cf.CashFlow_AccID,
	h.Date,
	h.total_value,
	l.cashflow,
	h.UnitNr